You need to check if you have any R134a in your system. First you need to use a proper set of gauges to check the amount of R134a that's in the system. If there is none, then run a vacuum pump to check for leaks. Refill the system and go from there. If you don't have enough R134a the system will not work properly. This is designed this way to protect the compressor. I bet you have a leak or crack in your rear AC Line.

Regards, JC.

 

Thanks JC. Unfortunately I don't have a manifold gauge set to check pressure on the high pressure side. (I can use my hose and gauge that recharges R134 into the low pressure side to check the pressure there.) I've already assumed that the most likely problem is low refrigerant. But to recharge the system I need the compressor running. The compressor doesn't run if the refrigerant is low. That sensor-detected cutoff protects the compressor. So I want to bypass the sensor and make the compressor run so I recharge the system. I'll do this with refrigerant that has an indicator dye to help identify any leak. This strategy also reassures me that the compressor and clutch are actually working by taking the sensor out of the picture. Yes, you sure wouldn't want the compressor to run for any significant length of time without refrigerant, but the only way I have to recharge the refrigerant is to have the compressor running.

 

Thanks JC. Unfortunately I don't have a manifold gauge set to check pressure on the high pressure side. (I can use my hose and gauge that recharges R134 into the low pressure side to check the pressure there.) I've already assumed that the most likely problem is low refrigerant. But to recharge the system I need the compressor running. The compressor doesn't run if the refrigerant is low. That sensor-detected cutoff protects the compressor. So I want to bypass the sensor and make the compressor run so I recharge the system. I'll do this with refrigerant that has an indicator dye to help identify any leak. This strategy also reassures me that the compressor and clutch are actually working by taking the sensor out of the picture. Yes, you sure wouldn't want the compressor to run for any significant length of time without refrigerant, but the only way I have to recharge the refrigerant is to have the compressor running.

The gauge set is around $50 at Harbor freight. It's worth the money trust me.

Regards, JC.

 

Thanks JC. Anybody know the electrical setup for the 2000 Sienna airconditioner? I'm looking for the air conditioning compressor clutch relay. In some models it's located in the engine compartment fusebox. Not in the 2000. Appreciate any help from those of you who are familiar with the air conditioning system in this model/year. Thanks.

 

I have the same question for my 2000 Sienna. I just replaced the Power Door Integration Module. The doors work great and so did the A/C for two days after replacing the module. Now the A/C light is blinking. There is plenty of coolant (R134a). A few seconds before the light begins blinking the compressor works and you get some cool air. I am convinced it is the Magnetic Clutch Relay but cannot find it. It isn't under the hood and doesn't appear to be in the fuse box behind the small change tray under the steering column. Does anyone know where to find it???

 

Send me a pm with your email and I will send you a link to the manual.

Regards, JC.

 

JC, do you know where the compressor clutch relay is located on your Sienna? Do you know how to override the sensor to make the compressor run when the refrigerant is low?
(In your last post, are you talking about sending me a link to buy the shop manual? I'm hoping to find someone who knows the answers to these two questions without buying the shop manual but I appreciate your help.)

 

My 2001 Sienna had the same symptom as yours. I used one of the AC recharge kits from the local auto parts house. After a few seconds of charging the system the compressor clutch kicked in. It took 2 cans to refill the system and then another about six months later. It has been a year now and the sight glass is still mostly bubble free so the recharge which also had leak sealer in it apparently has worked.

 

did anyone ever locate the AC clutch relay for a 2000 Sienna? The AC in mine works intermittently and I've read that the relay could have gone bad. It's a simple $20 fix, but I don't know which relay to replace. There are 3 or 4 labeled "fan 1, fan 2..." just need to know which one controls the magnetic clutch for the AC. I've been googling for about an hour with no luck... Thanks.

 

Maybe just jumper the pressure switch make it think plenty pressure or just shoot a lil gas in and watch it start up compressor need not be running as gas introduced it closes press switch to allow comp. to on and sux gas (freon)

 

JC, "I bet you have a leak or crack in your rear AC Line", can you elaborate on this?

My AC has a leak and I have noticed the rear line, behind the rear wheel has had oil/dirt collecting. I thought it could be a leaky seal or worse a cracked line, possible from winter ice collecting in this area.

 

I'd clean off the area where you suspect the leak. Spray it with brake cleaner to get it bone dry. If you are losing enough R134a to make the ac not work there's got to be more than just something the size of a quarter.
You can buy UV dye that you put in or get R134a with dye in it. That can help you find where all the R134a is going. The small can of dye they have at Napa is good because you can probably use it for a few years. The Napa kit I bought came with a black light flashlight and protective goggles but I seldom use either.
If you buy gauges make sure you get ones where the left (blue) gauge goes below zero, not just to zero, so you can measure vacuum. Otherwise the only way you check for leaks is to waste freon.
Where I live O'Reilly auto parts will lend you the gauges and an evacuator for free.
On my 2000 Sienna the problem was a leak inside the front evaporator where the expansion valve sensor attached to a metal pipe. All the parts that failed were there for reasons that were simply made up, there is and never was any need for any of those parts to be on any vehicle let alone to be hidden under the dash. It is a 100% bogus con job.

 

Tighten the drive belt. My experience is that the belt must be tighter than you might think.

 

Ac clutch relay is built in to the ac amplifier on passenger side behind kick panel. It can not be replaced it could be rebuilt if you are good with electronics but one from scrap yard fixed mine paid 50 for it.. also replaced the ac pressure switch at same time. On the 98- 2000 there is only one pressure switch