- Click on your avatar for Account details
- Click on Account Settings
- Type in your van's year and trim level under Vehicle Details
- Click the privacy settings link directly below Vehicle Details
- Allow all visitors to View your Vehicle Details on your profile:
AC clutch won't engage - not usual suspects
The AC relay and fuse are good. I took the van to a Jiffy Lube and the refrigerant is full. I've never had a problem with the A/C until it just stopped working a couple weeks ago on a hot day. What else can I check? Vehicle has not quite 150,000 miles.
1 - 17 of 17 Posts
Visually check to see if the clutch is engaging when the a/c is turned on.
Sorry, it's a 2004 XLT. The clutch is not engaging. I have swapped the horn relay with AC relay to no effect. Should I run wires from the battery to the compressor terminals? 
first do what Paul suggested and see if the clutch is turning visually. If not….
In my post I was suggesting jumping the sensor that engages the clutch with a metal wire (around the 1 min time stamp in the video). If you try that, you will be able to narrow down the source of the problem.
If your clutch engages when you jump it, you know you have a good clutch and probably good compressor and the problem is either that the sensor that measures refrigerant pressure is bad and or maybe you don’t have enough refrigerant pressure. Either way, you’ll know that everything works downstream if you can just generate an electrical signal to the clutch to engage.
If the clutch does not engage, the problem is narrowed to the compressor/clutch itself.
The jump test is easy and accessible. Should only take a few minutes to perform and can help diagnostics significantly.
In my post I was suggesting jumping the sensor that engages the clutch with a metal wire (around the 1 min time stamp in the video). If you try that, you will be able to narrow down the source of the problem.
If your clutch engages when you jump it, you know you have a good clutch and probably good compressor and the problem is either that the sensor that measures refrigerant pressure is bad and or maybe you don’t have enough refrigerant pressure. Either way, you’ll know that everything works downstream if you can just generate an electrical signal to the clutch to engage.
If the clutch does not engage, the problem is narrowed to the compressor/clutch itself.
The jump test is easy and accessible. Should only take a few minutes to perform and can help diagnostics significantly.
When I jump the AC pressure switch the two big fans turn on and that's it. The clutch does not engage (of course the pulley is spinning). No AC.
Try this insread. Make sure you get the polarity correct for the battery test. Disconnect the wires to the clutch for this test.
Okay, so I managed to disconnect the power clip to the AC compressor. There is only one positive wire. I tried to jump the compressor directly from the battery. Looks like the unit is dead. No click, no nothing. So what now? Replacing the compressor is easy, but if I have to do a full evacuation I don't have the tools or the time.
Does anyone know if I can only replace the AC compressor without evacuating and recharging the Freon?
Does anyone know if I can only replace the AC compressor without evacuating and recharging the Freon?
No, you can't replace the AC compressor without evacuating and recharging the Freon.Okay, so I managed to disconnect the power clip to the AC compressor. There is only one positive wire. I tried to jump the compressor directly from the battery. Looks like the unit is dead. No click, no nothing. So what now? Replacing the compressor is easy, but if I have to do a full evacuation I don't have the tools or the time.
Does anyone know if I can only replace the AC compressor without evacuating and recharging the Freon?
The compressor clutch itself can be replaced without removing the compressor, but, if you don't have the tools to replace the compressor you likely won't be able to do this repair either.
Did you check for voltage at the one positive wire terminal in the clip? (engine running and ac turned on for this).
You cannot replace the compressor without removing it so recharging and will be necessary. You can however remove the clutch without disconnecting the compressor from the system but then again you said you dont have the tools. Looks like a shop will be the way to go for you. If there is power at the terminal then thats a good thing. You could save some dough by replacing the entire compressor with clutch yourself then have a shop recharge it.
You cannot replace the compressor without removing it so recharging and will be necessary. You can however remove the clutch without disconnecting the compressor from the system but then again you said you dont have the tools. Looks like a shop will be the way to go for you. If there is power at the terminal then thats a good thing. You could save some dough by replacing the entire compressor with clutch yourself then have a shop recharge it.
If you have a multimeter, and you want to be 100% sure you’ve correctly identified the compressor as the problem, you can easily test the resistance of the clutch as the first vid Paul linked to describes around the 4 min mark. I like to be 100% sure before I send it off to the shop.
Thanks everyone. It's about time I bought a multimeter
Personally, owning a multimeter ranks about the same as owning a pair of pliers or screwdriver.Thanks everyone. It's about time I bought a multimeter
I can recommend this one: https://www.amazon.com/AstroAI-Mult...ter+6000+counts,+model+dm6000ar,aps,86&sr=8-1
Multimeter for the win! I'm not even getting 1 volt at the positive wire to the AC compressor, with the car running. Relay is good, so what do you think it could be?
CORRECTION: I am getting 12 volts at the positive wire. I realized the AC pressure sensor wasn't closed, so I jumped it with a paper clip and now I'm reading 12 volts.
With the engine not running, I also tested resistance of the pressure switch itself, and I got no reading (infinite resistance). This makes me think the pressure switch is bad, since wouldn't it be closed - and thus measure resistance - if it was working? I assume it's a mechanical switch that stays closed as long as the pressure is within spec. Assuming the pressure switch needs replacing, I'm still not sure why I cannot jump the AC compressor by bypassing the pressure switch. Or would the PCM cut the ground to the compressor if the pressure is too low? Hmm....
ANOTHER UPDATE: Okay, so I think I correctly measured resistance of the AC compressor, engine off, no resistance. I placed the multimeter terminals on the positive socket and one firmly on the grounding screw. This would confirm that the compressor is indeed bad, correct? No other PCM magic to throw the reading, right? Is there a neutral wire that I'm not seeing?
Also, can I remove the AC pressure sensor without losing refrigerant? Looks like there is a check valve....
With the engine not running, I also tested resistance of the pressure switch itself, and I got no reading (infinite resistance). This makes me think the pressure switch is bad, since wouldn't it be closed - and thus measure resistance - if it was working? I assume it's a mechanical switch that stays closed as long as the pressure is within spec. Assuming the pressure switch needs replacing, I'm still not sure why I cannot jump the AC compressor by bypassing the pressure switch. Or would the PCM cut the ground to the compressor if the pressure is too low? Hmm....
ANOTHER UPDATE: Okay, so I think I correctly measured resistance of the AC compressor, engine off, no resistance. I placed the multimeter terminals on the positive socket and one firmly on the grounding screw. This would confirm that the compressor is indeed bad, correct? No other PCM magic to throw the reading, right? Is there a neutral wire that I'm not seeing?
Also, can I remove the AC pressure sensor without losing refrigerant? Looks like there is a check valve....
1 - 17 of 17 Posts
Toyota Sienna Forum - siennachat.com
SiennaChat is the forum community to discuss problems, maintenance, repairs, mods, projects, specs and all things Toyota Sienna.
Full Forum Listing
Recommended Communities
