I have a 2001 Grand Caravan with a 3.3L V-6. I heard the belt squeal and the AC compressor make unusual noises a few seconds after I turned the AC on. I shut the AC off and had the wife turn it on while I watched the fans. The fans never started and when the AC clutch engaged and the belt and noise happend again. I was hoping that since the fans weren't on that the high side was building too much pressure. Question 1, are the fans supposed to come on as soon as the AC is turned on? Question 2, I see that there is an AC pressure transducer along with the powertrain control module that control the fans in AC mode. Can I jump some terminals at the PCM and/or the transducer to test the operation of the fans? I have verified that the fans run when the engine heats up so they and the fan relay/fuse are good. Question 3, are there any other relays/switches that control the fans in AC mode? Question 4, where are the PCM and the transducer? I tried the AC again and when the clutch kicked in the engine died, pretty sure the compressor is locked up now. Question 5, any comments?
Thanks in advance

 

Looks like fun times had by all. Question 1 = The fans come on when the high side pressure goes above somewhere around 250 psi, it varies depending on all the variables but in that area. Question 2 = you have already verified the fan operation, what you want and need to do is verify the transducer operation, you'll need a scan tool for that. Question 3 = The PCM controls all fan operation, the relay / fan module is located behind the front fascia to the left of the drivers side headlamp housing. Question 4 = The pcm is under the hood right in front of the battery and the transducer is a 3 wire sensor on the liquid line between the drier and the front h-valve. Question 5 = you need to check the transducer readings because that is probably an issue. It also wouldn't shock me if your compressor locked up. that was a huge issue with those, that's why they extended the warrenty on them. If it is locked up, there was a kit that was supposed to be installed to help the problem, new discharge and suction hoses along with a compressor and drier, I would recommend installing the kit.

 

Thanks for the reply, Tizzy. I have found the PCM, the relay, and the transducer, your descriptions were perfect. I have more questions!!!!!! Question 1, how do I test the transducer with a scan tool, does the compressor need to be functional so the transducer see's the required pressure? I don't have a scan tool but have been wanting to get one so this is a good excuse. Question 2, how long was the warranty extended? I'm sure I'm way past but it doesn't hurt to ask. Question 3, If they have a fix for the problem (the kit), what was the problem? I gues I'm still trying to figure out if the system had a known problem and the problem caused the compressor to tear itself up, or if it was excess highside pressure from the fans not coming on. It may be that the fans didn't come on because the transducer never saw the required pressure. Question 4, any idea how long the compressor can pump before pressure gets too high without the fans running?
Thanks in advance again

 

1 = with a scan tool, it actually tells you the pressure. A/C pressure and outside temp come close to equalling each other with the system not running. So a 70 degree day is 70 psi, a 20 degree day is 20psi. 2= they made the compressor a 7 year or 70000 miles warrenty, so you are out by time. The good thing is you can buy the kit for cheaper than just a compressor, the bad news is, the last time I checked they were on back order. 3= The issue was, the compressor was pumping all of it's oil out and not enough was making it's way back so it siezed up from lack of oil. So they redesigned the 2 compressor lines to hold more oil back. At 500 psi, the high pressure switch will turn off the compressor and there is a pressure relief valve on the compressor as well to relieve high pressure. It can get there in under a minute, probably didn't cause the failure, just bad timing.

 

Thanks again Tizzy. I'll be checkin' around for the kit at some dealers. I'm sure if I tell them what I want they will be able to find a part number. In case they don't know do you have a part number for the kit? I hope when you say it's back ordered that doesn't mean that I'll be in the middle of summer without AC Your info has been very helpful,
Thanks!!!!!!!!

 

Sorry 'bout that, the part number is 05179735AB and the cost is $562.00. I checked and they are still on back order but there were dealers that showed they have them so you should be able to get your hands on one if you want.

 

Soooo, I get a kit, take it to a reputable shop. They flush the system and say that the condenser should be replaced because of all the metal they are getting out of it and they can't garantee the work if it isn't changed. They say the rear is good. Now I'm wondering if the evaporator might need changing also (I hope not). I'm not familiar with flushing procedures but I would think that there would be issues with the evaporator. Should I buy a condenser and install it myself and save some money? Can they flush the system without contaminating the new condenser? Thanks in advance for any thoughts or suggestions.

 

How much debris came out of the system? I have replace many compressor's at the dealership. I didn't need to replace evap or condenser. How much more labor do they want to replace the condenser?

 

I hear that, that's what the filter is for. And if anything makes it to the evaperator, it get's caught in the h-valve. I've had to replace plenty of those. And if your getting alot of crap, probably need a rear h-valve too. Have to see how it works when your done, if it stops cooling, it's h-valve time

 

Thanks for all the great advice. I wound up replacing the compressor, condensor, both expansion valves, and the filter/dryer and it's very cool in my van now. I elected to let the shop install the condensor for $120.00 (I figured it was worth it). It turns out the fans weren't coming on because the compressor wasn't compressing (it was too tore up) LOL. After a $1300 and some change investment I can now ride in comfort. This forum has been a great resource for me. It's Armed Forces Day today so it's a great opportunity to say Thank You to all of the Soldiers that are protecting our freedoms, so that we can have forums such as this one!