1999 Rodeo AC

[shawfam]

1999 Rodeo, 3.2, 2wd, almost 90 k miles

AC will work fine, but after driving for 20-30 minutes, it blows warm. I think the ac fan is turning off when it is blowing warm. The blue light on the AC controls has been out for about a year, but this problem is only about 2 months old. Florida in the summer is not going to be fun with hit and miss AC. Any suggestions? I'm wondering if its an elec. connection or something, b/c it works so well - when its working....

Thanks in advance

[Ramblin Fever]

Anything else goofy? What's your volt gauge registering at normal driving?

[shawfam]

volt meter is registering normal

[kvrleo]

1999 Rodeo, 2wd, 97Miles

Hi. I’ve just started to experience the same problem with my Rodeo. When I talked with the mechanic over the phone, he suggested it might electrical and will look at it later this week. Any assistance or advice with this issue would be great. I appreciate your time.

[timallen82]

I just bought a 99 Rodeo and I am having this exact same problem. I too am in Florida, and it is getting HOT.

My Rodeo is a 1999, 2.2 litre 4-cylinder with app. 170k miles.

I have not figured out what is causing the compressor to go off, but I think it has some correlation with the 'supposed' engine temp. The reason I say 'supposed' is because my temp gauge is not working correctly. It will move back and forth, even when the engine can in no way be hot already because during a fresh cold start in the morning, the gauge moves up quickly and then moves back and forth intermittantly.

When the gauge needle gets into the hot zone, the A/C stops blowing cold. I am thinking that the computer is shutting off the A/C compressor as a safety measure when the engine seemingly gets hot.

Now, I have replaced the little brass temp sensor that connects to the gauge, but I am still having a problem with the gauge fluttering, so I either have a bad new sensor, or a bad wire or ground somewhere. I still need to investigate.

The other weird thing is that I purposely disconnected the sensor wire to the temp gauge to see if the A/C still cut off when the engine got "hot", and it does.

This tells me that the reading on the temp gauge has no correlation with the A/C shutting off, so my next step is to replace the temp sensor that goes to the computer, along with the OEM thermostat I picked up yesterday.

I will post my results sometime this weekend.

[brcidd]

You say it cools for awhile then- gets warm- and the blower seems to not be blowing anymore- right???

If so that is the classic symptoms of evaporator freeze-up-- when it does this- stop and look under hood- is the a/c lines white with frost? is compreeeos running? -- is it really humid in florida now? now shut off the engine- does the evaporator drain piss like a racehorse? leave a huge puddle?- then a/c works again after a twenty minute rest? this is freeze-up- your electronic thermostat on the evaporator housing must not be shutting off- or cycling the compressor like it should.........and remember, you can't blow air through ice!!!

[timallen82]

Originally Posted by brcidd

You say it cools for awhile then- gets warm- and the blower seems to not be blowing anymore- right???

If so that is the classic symptoms of evaporator freeze-up-- when it does this- stop and look under hood- is the a/c lines white with frost? is compreeeos running? -- is it really humid in florida now? now shut off the engine- does the evaporator drain piss like a racehorse? leave a huge puddle?- then a/c works again after a twenty minute rest? this is freeze-up- your electronic thermostat on the evaporator housing must not be shutting off- or cycling the compressor like it should.........and remember, you can't blow air through ice!!!

Hmm, interesting points. Perhaps it's just coincidental with the seemingly hot engine.

And yes, it is already hot and humid here in Florida!

I haven't noticed any frost on the lines, but I will start checking.

Funny thing. Yesterday, I ran some errands - mostly driving over 60 mph, and the AC worked on high for a constant 45 minutes or so. I stopped for about 20 minutes, got back on the road, and made it home in about 40 minutes with no problems. This was the first time the A/C has worked constantly (cold) for that long since I bought the truck.

Now, all the other days experience with this, when the A/C is blowing nice and cold, once the compressor cycles off or I turn off the car, I DO hear what sounds like draining coming from behind the passenger side dash.

At the times when the A/C stops blowing cold, the temp gauge has read hot. Coincidence? Maybe. In any event, I stop the car for a moment - engine running - A/C off for about 5 minutes, turn the A/C back on and it's cold again. Also, when I come off the highway and into stop and go traffic, I'll see the temp gauge get out of the hot zone and then the A/C blows cold again - without my turning anything off.

As I mentioned, perhaps the A/C problem is coincidental with the erratic gauge reading (possible bad sensors). I thought the computer was shutting off the compressor when the engine was thought to be hot, but you're suggestion makes sense.

What should I do at this point?

Thanks for replying, especially since you are an A/C engineer!