Air Conditioner blowing warm air

[smashman]

2001 RT/10 Castle Rock, CO
Air conditioner was fine a week ago. Drove today, it's blowing warm air, or I should say, same temperature air as outside. This exact thing happened many years back, and reliable Glyn Pribenow took care of it, a mouse or critter had chewed a vacuum line, I think it was for the blend door but I'm not 100% sure.

Is this vacuum line inside the dash, and could I check it without tearing the whole dash apart?
If I can't fix it myself, is there a good viper tech in the denver/south denver area?

Unrelated perhaps, but before I got going on anything, I was going to check the ac clutch relay just in case it was something that simple. But when I try to wiggle it out, the plastic cover just pops off, exposing the guts of the relay. Same thing with two others I tried. Is that normal?

Thanks in advance for any help. Before posting, I did try to search the forums, but it brought up hundreds of seemingly unrelated threads, so apologies if I'm starting a new thread for something that's already here 20 times that I can't find.

 

[Steve-Indy]

To my knowledge, there is no blending in a Gen I or II.

And no, covers on relays generally don't just pop off as easily as I think you are describing.

Do you have r-134a in your system? Have you tried to measure the low side pressure while the car and A/C are running?

Do you hear the compressor clutch clicking on and off?

These and other questions are best discussed person to person in my opinion as they often lead to more questions and solutions.

Feel free to call me if you like as I am a big fan of servicing our own Vipers' A/C at least once...especially if you can't get to an experienced tech soon. So far, I have driven 5 this year and they are all blowing cold on 80+ degree days...a couple of which are 22, 24, and 25 years old. 317 402 9013

 

[smashman]

That would be great Steve, thanks for the offer. I'm not a total dummy and have done some car work, I'm just no good at diagnosing. It may be something as simple as it's low on refrigerant, but I'm not sure how to test that either. Is there a good time tomorrow to call? To answer your questions as best I can in advance:

I know last time the tech said it was a chewed vacuum hose that was causing the problem, I cannot remember exact details beyond that.
The system has never had to be recharged, so whatever refrigerant was used from the factory, is still in there.
I don't have a gauge to measure the pressure (unless a 3/4" garden hose type fitting gauge will work) but I can get one at advance auto or NAPA, I'm sure.
I will start the car tonight and listen for the compressor clutch.
Thanks again for the offer, it is very appreciated.

 

[Steve-Indy]

Call me tomorrow anytime between 6:00 AM and 8:00 PM EDT.

Keep in mind that I am not a mechanic, but I have done/still do a fair amount of maintenance on all of our Vipers.

I think a few simple steps will answer a couple of questions that should get you going in the right direction.

 

[smashman]

Thank you. I may very well take you up on that. FYI, I checked and the compressor does engage when the AC is turned on. (At least it spins) I marked the black part (is that the clutch?) of the compressor in front of the pulley with a spot of yellow paint so I'd be able to see if it was moving or not. Let the car idle for a few minutes with AC off, and the black part was not turning. When I turned the AC on, the black part spins but no cold air. It did not click on and off, it just spun continuously.

I sat in the car and with the heater fan on high and the temp at cold, I cycled through all the modes.
To left center the "face" mode blew air from the face and floor ducts. The AC mode (the snowflake) put air (warm) out of the face vents but none out of the floor ones, which it seems when the AC is working, it comes out of the floor vents as well. Recirculate none from the floor ones either.

Now this seemed strange. To the right of center the floor setting seemed normal, but when rotated to either the floor/defrost or straight defrost I could hear a strong sound of air sucking from under the hood, and the exhaust tone actually changed and became far more raspy and choppy.

 

[Steve-Indy]

I will look forward to speaking with you.

Just for the record...the floor vents are only a source for heat...along with the windshield if selected. These only come into play when the selector knob (furthest from the driver) is turned to the RIGHT of top-center.

The dash vents are only for cool or cold air.. They only come into play when the selector knob is turned to the LEFT of top-center.

The Red-Blue "temp" knob is a source of confusion to many. It only controls the water valve that opens or closes flow to the heater core. It has nothing to do with cooling even though it has a blue position. Because corrosion in the heater core can occur due to isolation from the protective ingredients in the "antifreeze" thus a causing a core failure (leak), it is best to keep this on the red section of the dial...noting that the A/C will still blow cold air if the "snowflake" is selected. If this sounds very strange...because it is strange !!

 

[MoparMap]

If I remember correctly the earlier gens had issues with the o-rings on the back of the compressor fairly often. That would lead to refrigerant leaks and poor system performance, though I think if you lose enough the system won't even engage the clutch as a safety measure.

The funny idle you describe does kind of sound like a possible vacuum leak, though these cars run off a MAP sensors and not mass air flow, so they can kind of adjust for vacuum leaks a little better.

 

[Steve-Indy]

I appreciate your observations. There is a mode door actuator motor that possibly may need to be recalibrated per the service manual by disconnecting the negative battery cable for 60 seconds. This sounds like instrument panel removal is necessary to access this IF it is the problem and it is not able to be recalibrated.

The vacuum line to the heater control assembly may be what you are hearing as you suspected. This is something that I have not had to explore. I will ask a Viper Tech about the best approach to this line if you cannot spot it yourself.

 

[kssssnake]

My simplistic answer. If the compressor is turning and there is no cooling you are low on refrigerant, but not low enough to shut the system down because of low pressure. Gauges are a must. Get a cheap set at Harbor Freight and learn how to connect them properly. One A/C line will be cool and the other hot if the compressor is working. Look for water forming on the cold line. Gen I systems actually have a sight glass. Not sure about later years. Last time Steve and I met we both had a can of 134a in the trunk in case it got warm on the way home.

 

[Steve-Indy]

The other issue is the vacuum leak. It will be interesting to see if you can find the source of the "strong sound of air sucking from under the hood". Are you sure that is not from the airbox?

 

[smashman]

OK, here's the update:

First-Thank you for all of the generous replies and offers to help.

I called Glynn Pribbenow, the guy that was the go to Viper Tech here in CO for years, who is now in TX. He thought it also might be low refrigerant from a leak or possibly a vacuum issue. He did clear up the question about the "sucking sound" and exhaust note/idle variation when changing modes to the right of center on the mode dial. When the mode is all floor, the idle was smooth. But with a defrost/floor mix or full defrost, it got more raspy. Glynn said that anytime defrost mode is engaged, whether the temp dial is full blue, full red, or anywhere in-between, that the a/c compressor engages to remove condensation to reduce window fogging. So of course at idle if the compressor kicks in it'll bog the motor a bit. Mystery solved there.

I admit I was not comfortable messing with adding refrigerant, dye, etc, and I could not visually see any damage to any vacuum hoses, so I took it to the local dealer that has a viper tech. The problem was:
Cause: Verified concern. found a/c system to have 5ozs of refrigerant in it. spec is 1.81 lbs. no signs of leak detection dye leaking from vehicle anywhere. refill refrigerant, inject leak detection dye and operate a/c looking for a leak. found leak at suction line near a/c compressor.
Here's the pic they emailed me:

You must be registered for see images attach

So there we go. Three times I've had a/c issues and each time it was somewhere different. Once it was a vacuum line chewed by a varmint of some sort. I can't recall the cause the other time but I think it was a "damaged" vacuum line of some sort, probably with a varmint as the culprit that time as well. This time does not seem to rodent-related but that is an issue. Someone suggested using aluminum tape but I think I'm going to look into some steel-braided sheathing that I can slip onto some of my lines. Plus maybe our fat, useless cat needs to spend a night in the garage once a week.

Last question is will Delta Auto Protect actually cover it or will they try to snake their way out of paying?

 

[Mark Crosby]

Take the front bumper off and replace the condenser O rings. Replaced mine, recovered what was left, pulled a vacuum on the system, added oil, charged system. Blows ice cold. O rings on that ac condenser are public enemy number 1.

 

[David Posea]

I first lost a condenser to a rock, then my AC started blowing hot air after 6 months. The AC was not used much during that time. It turned out to be WAY over charged.