Would a mechanics recommend compressor replacement without complete check?
Essentially, my car AC is not working. Toyota mechanics want me to pay an
arm and a leg blaming the compressor. In my quest to cross-reference
data sheets and wiring diagrams, it dawned on me, did they check this
information? Or do they just *blame* compressor and do the real analysis
once the money is coughed up?
I own a 2009 Toyota Camry Base Edition. It turns out my AC compressor is
a swashplate AC compressor, meaning it doesn't have a clutch but instead
its piston displacement is variable based off the angle of the swashplate.
Link to a swash plate compressor: https://www.youtube.com/watch?
Now I'm on a quest not to spend $900 to $1600 to fix my AC issues
(especially in freaking SUNNY Florida - oh the humanity) but that is the
quote I'm getting from mechanics.
Now I'm a tech so me chocking up money for a system I can very well learn
myself and repair myself is not in my blood. I've fixed my 2001 Honda Civic
when mechanics wanted me to hand over $800 by replacing the fuse box.
Saved me $600 and I learned a lot about my car.
The following "Just Answer" forum post is right up my car's issue.
It appears that the issue could be the solenoid valve towards my
compressor. Toyota properly evac/recharged the system to rule out freon.
Did they check everything else or just blamed the compressor?
Most of the diagnosis on a vehicle AC system is traditionally done with a GAUGE SET. Some with the Factory Scan tool. Some with a Digital Volt Ohm Meter. If the Compressor is turning on and rotating...it will be proving specified pressures on the High Side and Low Side of the system. Those pressures will provide the necessary info for diagnosing a bad Compressor. If the compressor is NOT rotating when the AC is turned ON....different ball game. Try Googling Auto AC System Pressure Diagnosis. Get back to us with results.
If you can diagnose the issue yourself and find that the compressor is bad, try these guys for a replacement: http://www.meridianautoparts.com/ These guys saved me a ton of money on my '89 4X4. The steering box went bad and began leaking and truck would turn very hard to the right. I took it to Toyota for a diagnosis and they pretty much laughed when they told me that a new steering box would run me $2500! I removed my old box and sent in my old one for a core. It cost me $300 for a new rebuilt box. Lasted until I sold it a few years ago. Never a problem after I replaced it. I believe if you send in your old compressor, they will send you a rebuild for a fraction of the price Toyota will charge you. Keep us posted!
Leanman....curious...what did you decide to do with this vehicle?
Still trying to figure it out...any ideas? I think it might be the solenoid valve in the compressor. I've talked to the adviser from Toyota and he answered my questions well. He told me that the mechanic checks the pressures, reads any faulty codes from the computer ruling out computer problems. I can only think its the valve that controls the pressure into the compressor...either that or it really is the compressor.
If I ever have to GUESS as to what parts to replace for a specific repair....I always start changing the Cheapest part first. Good Luck.
yea I checked a lot of the system already. The pressure switch and computer is good because I probed the voltage going into the compressor. The voltage is high when I turn the AC to max and its 0 V when I turn off the AC. So that tells me control is working. SInce the pulley on the compressor is always spinning I don't have to worry about checking that (no magnetic clutch). Therefore the problem begins at the control input (i.e., solenoid valve) of the compressor. If its not that, then it is indeed the compressor (since evac/recharge rules out other parts of the system).
"no mag. clutch".....does your Comp. Look like this? Does it have 5 wires going to it? Red...Comp. Clutch 12-14volts DC Engine running. Green and Blue...Lock Sensor...not sure of Volt. Might be a reed switch. White and Black....FLOW VALVE. Black is a Volt. coming from AC Computer...my guess a varying DC Volt based on Comp. output. White wire...ground...near 0 volts.
The flow valve stuff is accurate. No 5 wires going to it, just the black and white wires you stated.
How many wires are on the connector going to the Compressor? What are their colors? What Engine is in this vehicle? A photo of your compressor and its electrical connector would help.
BTW....this vehicle should be setting AC Codes when it malfunctions. Does the AC light stay ON/Flashing when the AC is turned on? Codes should therefore be stored.
The AC light stays turned on when the AC is turned on. It doesn't flash however.
OK...AC light stays ON while AC is turned on indicates the Ac Amplifier(Computer) sees a malfunction in the system and has set a code(s). Would be nice to know these code ID's. My guess when you had this vehicle checked out at the TD they monitored Hi/LO side pressures and attempted to activate the Flow Control Valve with their Factory Di-Directional San Tool. They concluded the Comp. was bad based on?????who knows...you nor I were there. These Computer Control AC Systems have a variety of SENSOR inputs which the AC Ampl. looks at to determine where that Flow Valve should be. Sun Load sensor...Hi/Low side switches and sensors....etc. Without a Wiring Diagram of this AC System...and....not knowing what codes are stored...we can only guess what parts to start replacing. Typically....with a Gauge Set in place...with a bad compressor...Hi side reads LOW....Low side reads LOW pressures...it's either a bad Comp....or ....Low on refrigerant. So...the ball is now in your part of the world. Good Luck
Wait a minute.....correction. AC light stays on when AC is running????....That's NORMAL. Old people...you have to watch-em like a Hawk. AC light Flashing....that's NG. Well...may be we should take a look see at the Owner's Manual.
Leanman.....any good news concerning the issue with this vehicle?
Hey last_chance_garage, I apologize for not returning messages sooner. Its nice to hear someone who cares. Today I was bummed out after trying to get a mechanic to give me a quote. In any case, I have wiring diagrams, pictures, I've also measured signals, and found the part I want replaced. I'll post a synopsis and pictures of the conclusion.
Thanks for the feed back and update. This is only way we know if this Web Site is reaching its objectives....that is.....helping folks who need to make maintenance and repair decisions on their vehicles.
The solenoid valve of my AC compressor is located in the bottom right of the compressor. It’s an 8.3 cm long part that is slotted into the compressor. It controls the pressure in the crank chamber. By controlling the pressure in the crank chamber it can angle the swash plate. The angled plate generates the AC cooling effect by driving the compressor pistons.
The solenoid valve has two wires connecting to it. One Black, one White - see pic below. The white is ground. The black wire is duty cycle controlled. It is essentially an AC voltage. However, a good digital voltmeter will average the voltage in DC mode and it can be read between 0 volts (0% duty or off) to battery voltage (approx 12 volts at 100% duty or full on).When I put the AC at max, the wire gives a reading at 12 V which means it is working properly. Other things to think of: - Its not the clutch as it does not have one. - Its not a bad pressure switch as the solenoid valve is receiving signal from AC Amplifier. - Bad AC Amplifier (computer) - Not likely since solenoid valve is receiving signal from AC Amplifier and Toyota would have seen the codes when they did their diagnosis - Low on Freon - Not likely as Toyota charged the system to specs during their diagnosis and AC stopped suddenly which indicates a failure of a part rather than a leak in the system. - Compressor Failure - Possible but compressor never made any noises and its clutch-less so less moving parts. It hasn’t seized and still spins with the belts. - Solenoid Valve - It’s what controls the angle of the swashplate, if the compressor is still spinning and its swashplate is not angling any longer than the solenoid valve has failed. No other part explains this behavior.
Solenoid Valve: The solenoid valve is about 8.3 cm. In order to replace the part, the Freon needs to be recovered and then enough clearance needs to be obtained to remove the valve. The valve is held into place with O-rings. My question is can this be done? Would someone be able to replace the valve without having to take out the compressor and just move other parts of the system out of the way just so they can replace the valve? How much would this cost? How should I go about asking a mechanic to do this task for me since they seem adamant to a diagnosis even though I feel I have all the diagnosis I need. This is an example of replacing a solenoid valve a chevy compressor. https://www.youtube.com/watch?v=uPUHOnei3g8&t=140s
I prefere to check duty cycle controlled devices with a Scope...or...digital Grafing votmeter meter. Then I could observe the DC change as I switch the ac controls from min. To max. Indeed..finding some one who will go through the trouble of Evac. and charge an AC system....just replace a valve.....well that is why ....the diagnosis of bad comp. IMO .....l would rather remove the comp. In order to make sure that valve is installed properly. This would be the only way to verify your diagnosis of the valve being the root cause of this Ac issue.
I see would it be better to replace the compressor then?
Your choice. The price of a Compressor vs. the price of the Valve. Let us know what happens.
Ok. I just wasn't sure if at this point between pros and cons which direction would be better. I mean if I replace the compressor, I would have additional work to pay for such as replacing the dryer, etc. I'm just not sure if there is a way to confirm the valve has failed. Is there a way to test the valve to see if it makes a sound if its working, etc?? Thanks! Also, I unhooked the solenoid valve connector - is there any concern that this will damage the A/C system? Thank you.
What we do to confirm operation of that valve is to attach a scope or a DMM with duty cycle capability...a AC Pressure Gauge Set installed into the high and low side of the AC system. Someone inside the vehicle turns the ac on HI...and allow pressures to stabilize. Then the AC is cycled back and forth between between its various cycles...Max.....Heat...etc. The duty cycle of that valve should respond by following the commands requested at the Dash controls. The DC is the COMMAND from the AC computer. If the AC Sytem is properly charged...and...we have ruled out other control components...one would assume the valve is faulty.
BTW...I see no problem leaving the Valve in question DCed. The AC warning light will most likely start flashing and the computer will set a code(s). There is another test you can run on that valve. There should be a RESISTANCE spec. available somewhere. Also...if you have access to a signal generator...you could attach same to the valve and command different duty cycles then check the effect on the AC output. With the Engine not running...you should be able to hear the valve clicking at different rates as you change DC. We us an Automotive Stethoscope. Makes us look like we know what we are doing.
Not sure why my images got deleted but here they are again. Picture of the compressor in my car.
Picture of the actual solenoid valve. Correction its actually 12.3 cm (4.83 inches)
Interesting....I wonder what holds it in? A snap ring perhaps?
I've been told its an O-ring which seems similar to a snap ring. What is the difference?
I'm inclined to think there is something else keeping it in the compressor. Take a mirror and a flashlight ans see if you see something circular on top of the connector end of the valve. An "O" ring is made of rubber and is a sealing device. A Snap Ring is a retaining device and made if spring steel.
last_chance_garage, would a car battery be safe to test a solenoid valve with? I mean if I do I am worried about the amperage it will dump into a load that I don't understand the resistances of. Would it damage the valve? I also have a motorcycle trickle charger that I can get 12 V DC from as well.
Attaching 12 volts dc to a duty cycle sol. is very risky....especially if the frequency is unknown. Why not measure the resistance of the sol. in the compressor then we can calculate the amperage that will flow through the circuit. The trickle charger idea....unknown. I am not aware of the circuit in the charger and how the out put is controled.
The replacement solenoid came in the mail. I just realized that the I could attach the part to the output of the AC Amplifier and look for signs of function that I can compare against the supposed failed part. Any thing to look out for like what should I see it do or tips, etc? Thanks. I also have access to signal generators and people who can help advise me at work.
Ok...make sure you properly ground the new solenoid. Hold it in your hand and have someone start the engine and operate the ac and heat cycles. You should feel the solenoid functioning. Carefully now..keep your hands away from ROTATING PARTS.
Also determined the resistance of the solenoid valve to be 12 ohms. It should be rated to take on 1 amp seeing that the battery is a 12 V battery.
OK...but remember. If that solenoid is indeed a PWM.... Pulse width Modulated Solenoid the Amperage would be anywhere between 0-1 amp. depending on the duty cycle. To bad we do not have a Scope to see what is really going on...eg...Commands ...from the AC Computer(Amplifier)
So I tried a real quick test today with my roommate before it got cold. The fan and AC light turns on without the engine turning on so we just tried to do this with the engine off. Since I was sticking my hand in there I didn't want to be ground beef trying to figure this out. In any case, nothing happened. I didn't hear any clicks or did I feel anything from the solenoid valve. I just grasped in the palm of my hands, not sure if I was supposed to do something else. Bottom line, didn't feel or hear anything when my roommate went from low AC to MAX AC. Should I have had the engine turned on?
I should have access to a O-scope but I don't want to go through the trouble of setting one up for this. I can't seem to upload files unfortunately so can't upload relevant Camry documentation I've found.
Did you have this solenoid properly Grounded? Since it is difficult to see from your posted photo... How many wires normally connect to this sensor? Glad you decided not to run the engine. No sense in taking any chances.
Ok...if your voltmeter will display volts and duty cycle place the leads into the electrical connector disconnected from the solenoid.. Using the DC function with the VM leads away from rotating parts..start her up and turn the AC on and cycle from warm to cold. You should see an appropriate response in Duty Cycle. This tells us the ac computer is attempting to respond to the controls on the dash.
In reference to your first question, the answer is there are two wires leading into the solenoid valve. The white wire is ground, the black wire is the AC computer duty cycled control signal. Was I supposed to connect something else to ground? On your second response, ok, I should have access to such a voltmeter. I will check the DMM I have at work see what functions it provides.
OK the white wire being ground should have been adequate. That ground can easily be checked with a DMM. Using the DC volts scale...red lead to battery positive...black lead to the white wire at the connector with the connector disconnected. You should see battery voltage...12.0...12.6 volts DC. Finding a way to check the control of that solenoid....black wire... without risking injury ....a voltmeter capable of DC function is almost as good as a scope.....as long as we can keep the wires away from rotating parts. Realize...folks out there are most likely thinlng we are nuts. Most would just go ahead and replace the compressor. This is more ......fun?
This is fun, especially when $1600 is on the line ;) and it helps its winter so I don't mind till when it gets warmer before putting up the big bucks. In any case, I hooked up the replacement solenoid with the engine on, and I was able to feel/hear the valve click which was a nice confirmation of it working. When my co-worker went from AC off to AC max, the DMM went from 2.7 V (off) to 13.3 V (on) and there was no variability in between. If he had the AC at half, the volts reading kept reading 13.3 V. I would have expected a change in the reading if the duty cycle was changing. In any case, this was something strange I noticed. Now that I know how the solenoid valve works, it’s hard to tell the same thing of the solenoid valve within the compressor because of the engine noise. Is there a way to perhaps energize the solenoid in the compressor without turning on the engine so I can hear the clicks and verify the part has failed?
The only way I know to safely energize that solenoid in the compressor is with a signal generator. If you do not mind taking a risk...disconnect the connector on the solenoid...and take a jumper wire and ground the ground terminal on the solenoid to the negative post on the battery. Take a 12 volt test light that has a regular bulb in it..not a LED. Attach the test light lead to the positive terminal on the battery. Now...with the point of the test light...find a way to intermittently flick the terminal that had the black wire attached on the solenoid. That should simulate a pulsing signal to the solenoid on the compressor. Just to make sure the test light is safe to use...use your meter..set for amps....put the test light and meter in SERIES.....with the battery...and see that the bulb is drawing less than 1 amp.
Careful now.....do not but that ammeter directly across a load...or...the battery terminals....by...by....ammeter. if you do not know what a series circuit is ...look it up.
I suppose so long as I stay below 1 Amp, any type of signal wouldn't hurt the valve. Even if I can't quite simulate a duty cycle signal. On top of this, I believe if the volt reading from the AC computer is 13.3 V, this is telling me that when I turn on the AC, it is sending a 100 % duty cycle to the solenoid valve. So I might just need a DC signal to the valve to energize it. Just a thought. I can probably get a portable O-scope if I really wanted.
I agree with your assessment. That is what that 12 volt test light would be doing. Sending 12v to the solenoid at less than 1 amp. Keep us appraised of your continued analysis.
Leanman....ok....give me the bad news first.
Hey last_chance_garage, yes it’s been a while. I hadn’t much progress but it’s due to work and doing other things worthwhile. But in any case, I have some more data but I think I might be ready to throw in the towel because I'm still not sure what's wrong unless you got any ideas. In any case, I did something awesome and borrowed an o-scope and put the A/C computer signal up against it. The pic is attached. What I noticed and I think this might be important is that from AC from LOW to MAX, the duty cycle of the signal never changes. It always reads 95.8% duty cycle. In addition, the baseline voltage is always 2.67 V. I'm not sure why the duty cycle doesn't change unless this is just how it works...I don't know. Another thing I did was I took my newly purchased solenoid valve and tried it against the A/C computer signal. I would get a total of .93 Amps flowing through. When I did the same thing with the suspect solenoid valve it always reads .85 Amps. I'm not sure if that difference is suspect but it could be. In any case, other than a couple breadcrumbs like these, I don't have much to chew on. Got anything for me? Thanks! See image for the O-scope measurements - Note that no matter what configuration of the controls (except off), these measurements did not vary. When the controls were off, the signal was a solid 2.67 V.
I just don't know what the signal is supposed to look like from the A\C amplifier (computer) so in any case, just posting to see what could happen.
Ok...very interesting. What I see is a square wave signal with a DC of about 90+ %...0-12v peak to peak. So indeed that solenoid is just about ON all the time. When you turn the AC control from AC to Heat...that traditionally operates a BLEND Door in the system. This may explain why there is no change when you turn the ac control head from cold to warm?? Hmmm. Perhaps that valve responds to some other control like a sensor in the AC System. I'm thinking perhaps the Sun Load Sensor at the Dash below the windshield.......or...an in car sensor elsewere. We would really have to look inside the compressor to see how this valve changes the angle of that swash plate. It would be interesting to monitor Hi and Low side refrigerant pressures when we operate controls and have that scope in place. That requires the an AC pressure test set.
I have the schematics of the AC system, both wiring and operational/mechanical. I can provide it to you through e-mail, maybe someone more intelligent than me can see what's going on. It would help you understand the AC amplifier (computer) system. Unfortunately, I don't have free use of the o-scope whenever I need it. I only went from AC MAX cold to AC min cold. I did go to the warm setting but I don't think anything remarkable happend. I don't have access to an AC pressure test set, so that's unfortunately impossible to do. Do you want the schematics? I also posted a pic of what range on the dial of the AC setting I took measurements on.
Just a few other thoughts. When you turn on the AC System.....does the AC LED Light Flash? Have you ever run a check on the Evaporator Temp Sensor? Not easy to get to. Located inside the Evap. Housing. This little guy senses the air temp around the Evap core and ...what if it's lying to the AC Amplifier? If it tells the AC Amp the evaporator is cold....when it's really warm?? Hmmm. How about the Ambient Temp Sensor? Easy to get to....right in front of the Condenser. We used to warm that guy up with a hair drier and watch the pressure change on our Gauge Set. What about the Sun Load Sensor located about in the middle of the dash near the windshield? We used to cover that one with a black sheet of paper....then...uncover and shine a strong flashlight right on it and watch the change in the pressure readings. How about the AC Room Temp Sensor? Tough to get to. That's buried under the center console. Ac Pressure sensor? That's located in the Refrigerant plumping. Toyota's SCAN TOOL checks these sensors easily and quickly. They can even read HI and Low side pressures on the Scan Tool. Can we assume they performed these checks and tests before condemning the compressor? Hmmm.
Regarding Schematics etc. firstname.lastname@example.org Glad to provide you with any help with this interesting issue. IMO ...without the factory Scan Tool...and....a pressure gauge set...we will have to continue to postulate the root cause of this issue. If you can find someone who is willing to Evac the system...replace the valve....recharge and test...that would be nice. I found an interesting video on line of a Tech R&R that valve without removing the Compressor. he DC the drive belt...un-bolted the Comp.....and ..R&R the valve from under the vehicle. Hat's off to that guy. Keep in touch.
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