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I’m a new member…Hello! I’ve followed ETCG on youtube for years, I feel like I’ve kinda been a member for awhile, lol. Anyway heres the situation:
2005 Toyota Sienna LE, 145K miles, recently the AC quit working and I’m going without sleep and going crazy trying to solve this puzzle.Coming home from a summer road trip (8,000 miles) the AC stopped working! Since I had a wife and 5 kids with me in 98F heat, I had to attempt a repair on the road. I first realized that the clutch wasn’t engaged. I swapped clutch relay with horn relay and no change. I then thought maybe it was a low pressure switch, so I got a can of 134a with the hose and gauge attached and the static low side pressure was high! We drove the remaining 1,000 miles home with no AC (old school, windows down) Back in Florida, where AC is a must! I first checked with my manifold gauges (static) 100psi low side, 100 psi high side. Then I checked for voltage at the clutch with key on…no power at clutch. I check for power at clutch relay…12 volts at feed to clutch and 12 volts at the coil side of relay. I jumped the feed side of the relay and get power to the clutch, with no clutch engagement! Bingo…bad clutch, right? As simple is that sounds….how would a working clutch solve this problem? There isn’t power going to the bad clutch now. Does anyone have any suggestions??? On another note and maybe a coincidence…when I first noticed the AC blowing warm air, I had just floored the accelerator to pass someone…I’ve looked at the schematic and this van doesn’t appear to have a WOT cut-out relay, but I could be missing something.
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100psi on both high and low side is normal when the compressor is not running and static equilibrium has occurred.
I am not sure I completely understand your question, though. I think you are asking if a new clutch will fix the problem? If so, the answer is, first the electrical controls need to be verified. With A/C relay removed, key on engine off, and A/C selected (turned on), check continuity to ground from pin “2” of the relay (per your picture) to a known-good ground. Check for ~12v against a known-good ground (do not use pin “2” for this) at pin “1” (per your picture). If that test is good, then the control side is okay. Now check for ~12v at pin “3” against a known-good ground (do not use pin “2” for this). If that is good, your contacts will have voltage applied. Next, using a heavy gauge piece of wire, jumper pins “3” and “5” together. Now check for ~12v at the compressor clutch connector. If you have voltage there, then your electrical circuit is verified. If any of those tests fail, there is a control issue. Check fuses and wiring for damage. If those are ok, check the low pressure switch. After the wiring and control circuit is verified and power is reaching the clutch connector, if the compressor is still not operational, the clutch is bad. Even if the clutch “clicks” when power is applied, the friction material may be destroyed and the compressor will not engage.
I would also recommend ohming the compressor connecter see if you have continuity and what the reading is. Also check both of the wires to the case of the compressor; if it is two wire there should be no continuity. If single wire you have to ohm the single wire and then with one lead in wire and one lead on the case you should have continuity in this case.. Also in some vehicles the computer will cut a/c operation under hard acceleration but, it should return to normal after you let up some on the peddle. Chrysler is known for this.
Look at the fins/connector at the relay and anywhere else to see if they are bent so much there will not be good contact and or corrosion. aka does it look like it will have spring tension on pins/blades or do you see green fuzzy stuff.. You can also try a drag test and see how easy it moves pulling them apart while you hold the lock open. There should be some mild resistance when pulling apart. Also I would check the harness right at the compressor it likes to wear there on most vehicles.
I’ve done what you suggest and it looks as if I have a control/ECM issue…the ECM isn’t gounding the control circuit when AC is commanded. This must be an uncommon problem.
On another note, I took the van to a local AC repair shop who told me that I needed a new compressor? I hadn’t told about all the troubleshooting I had done. He said I had voltage to the clutch, lol. The only way to get voltage to the clutch at this point is to jump across the relay! This is exactly why I try to do my own repairs!The next things to check are the A/C fuse located under the glove box, the A/C evaporator thermistor, A/C ambient temperature sensor, dual pressure switch, and A/C control module. Those have to be ruled out before considering the ECM. The ECM is always the very last item after a diagnosis by elimination. They are expensive, and 2005 and later have to be programmed by the dealership to match the vehicle’s VIN and odometer mileage. So we let it go until everything else has been ruled out.
Thanks for the advice, and attempting to keep me from over-reacting! The two fuses behind the glove box (7.5A) are both good. The ambient sensor (behind the grill) seems to work fine…resistance changes when heat is applied and the temp is displaying on the console. The dual pressure switch…I have voltage at both inputs…how do I further test that switch? Haven’t looked at the evap thermistor or AC control module, nor do I know where they are…if you have an idea of location, that would be awesome! Thanks
Ok, Here’s some stuff!
Ambient air temperature sensor:
Evaporator thermistor (The connector is mounted on the external surface of the evaporator case):
A/C control module (aka A/C amplifier):
The A/C control module / amplifier is inside the control unit (the part with the knobs). Here is a pic of the assembly:Testing information for pressure switch and A/C amplifier:
in PDF attachment below
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