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Discussion Starter #1
What are the proper High and Low AC pressures for 2001 Cadillac Deville? I have a chart attached from a member's posting.. Can anyone verifythe pressures ar correct from the FMS? What is what is in the FSM? I am going to get a copy soon but have not received it yet.. I am trying to add refrigerant to my caddy to stop the warm air coming out of the drivers side AC outlets. The low pressure was at 30 psi and I added R-134a to 40 psi, helped but did not stop the warm air, but I then got the chart below and in Florida where we are at 85-90 degrees it apparently should more like 50 psi on the low side..Hellllp.
 

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-Administrator- 2002.5 F55 STS 2014 FWD Explorer
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You cannot correctly charge/balance our systems by using a can and gauge. It's done by refrigerant weight from total system vacuum evacuation.

High/low pressures vary as a function of ambient and car cabin temperatures. You're shooting at a moving target.

Also check the cabin air temp sensor - inside the little grille by the steering column - for correct operation. It fills with dust bunnies - there are several How-Tos in this, Seville, and TechTips. Google "cadillac forums seville deville cabin air temperature fan module".
 

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What was your high side reading?
Have you checked the DTC's to be sure that you don't have a failing air mix door actuator?

If you don't have a set of gauges with both high and low readings, a quick and dirty way to get you in the ball park is to check both the inlet and outlet pipes at the firewall. They should both be cold. If the outlet pipe is warmer than the inlet pipe, you are still low on refrigerant.
 

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Discussion Starter #4
Hi, The high side was about 165 and low side 40, temp about 85 degrees.. Interesting Submariner409 suggests the only way is to evacuate the system and reinstall the 32 oz of R-134A.. Never have seen a AC shop do that.. I have not checked the DTC's. Will do that later today.. Is it best to look at the TDC's or check the OBT II codes.. Did look at the cabin temp sensor and blew it out with air even though it was clean..
 

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Discussion Starter #7
Just did the codes I had two
IRA-U1064 Dim communications
RFA-B3109 Battery
I have never checked the codes so I have cleared all and will let run for a while and see if they come back..
One other thing the drivers side air is cold when the car starts and driven for maybe 3-4 minutes then it turns warm not hot, just not cold.. The passenger side is very cold and stays cold.
 

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Discussion Starter #9
Thanks , I am back to my original question what Freon levels should be at 85 degrees and 70% humidity? I am presently at 40 low side and 165 high side.. Is the chart I included correct? that would answer the low freon issue, if not I will look at the blend door (more labor required to open up the dash).
By the way the car only has 39K miles..
 

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Most of us here are not AC techs but my readings a few months ago were about the same as yours with the same symptoms. I added a can of freon and the driver vent got cold and my readings went up to 50 and 190ish. The AC charts are not deville specific and are pretty much the same specs for all cars assuming the compressor is not damaged or worn out.
 

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Discussion Starter #11
Thanks for your input.. I guess it wont hurt to add enough freon to get to the 50 lbs on the low side and see what happens.. Was going to wait for my manual but it won't be here for a week.. I have never understood why you could get warm air from the drivers side AC and cold air from the passengers side AC if it was just low freon as the air would be passing over the one evaporator coil.. It made more sense to me that it would be a blend door or something that would only effect one side.. BUT I have seen in many of the postings here that the low freon does in fact cause this issue..
Would be interesting to see if anyone could explain why adding freon to low freon system fixes the low cold air output on the drivers side only, anybody out there have any ideas??
 

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The refrigerant flashes to vapor in the expansion valve/orifice. Cabin heat is transferred through the fins/coil to the vapor in the evaporator core. If the vapor flow across the core is inadequate then the first section of the core - the passenger duct side - gets most of the "air conditioning" and the far side gets less (heat absorption), thus Ranger's advice to feel the two refrigerant lines - if the downstream side is inefficient then that refrigerant line will be warmer than the inlet side.

Not saying the problem could not be a leaky blend door - but refrigerant checks and charging is the first step.
 

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Discussion Starter #13
Thank you for your input, I do have a AC license and understand how AC works but seriously thanks for the refresher course.. The part I do not understand is that there is only ONE evaporator coil in this car. so cooling is the same for all evaporator outlets. the difference is that the passengers side and the drivers side apparently have different mixing and air valves and are all controlled individually.
I brought the low side up to the 50 psi and the high side is now 210 psi. Same issue when I start out the drivers side is cold and the passengers side is also cold the fans are on high.. a few minutes later the drivers side gets warmer. the passengers side stays very cold. Also the fans dropped to a lower speed when the drivers side went warmer.

The input tubing from the expansion valve and the evaporator output tubing at the fire wall are both cold..
There are no codes..

Still sounds like the drivers side actuator or mixing valve is not working properly, but I don't have my books yet. so I can't check the actuator or valve and see if they are working properly..

I really appreciate everyones helping..
 

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Discussion Starter #14
Thank you for your input, I do have a AC license and understand how AC works but seriously thanks for the refresher course.. The part I do not understand is that there is only ONE evaporator coil in this car. so cooling is the same for all evaporator outlets. the difference is that the passengers side and the drivers side apparently have different mixing and air valves and are all controlled individually.
I brought the low side up to the 50 psi and the high side is now 210 psi. Same issue when I start out the drivers side is cold and the passengers side is also cold the fans are on high.. a few minutes later the drivers side gets warmer. the passengers side stays very cold. Also the fans dropped to a lower speed when the drivers side went warmer.

The input tubing from the expansion valve and the evaporator output tubing at the fire wall are both cold..
There are no codes..

Still sounds like the drivers side actuator or mixing valve is not working properly, but I don't have my books yet. so I can't check the actuator or valve and see if they are working properly..

I really appreciate everyones helping..
OH Yeah, I can make cold air come out of the drivers side by turning the cabin temperature down till the fans come up to high speed again..
 

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Had a similar problem, but the pass side was warm, bad door/temp actuators.

The system goes through a test/reset when it comes on for all the doors. It makes a difference where it was at on the previous setting, fan speed can hamper a weak actuator. You can hear it doing this, fan will be low, doors swap all around, fan will come up a few seconds later
 

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With your pressures AND both inlet and outlet pipes being cold, I'd lean towards the blend door actuator.
 

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Discussion Starter #17
Thank for the responses, I was also thinking the blend door actuator but if it were the actuator why would it start out cool then warm up, it takes about 4-5 minutes and the fan slows at the same time? Could be a weak actuator or partially working blend door.. Almost sounds like a sensor or electronics may be bad where it may be misreading the temperature. I looked at the cabin sensor it was clean and the little fan was running, blew it out anyway no change.. Hoping to get my FRM this week so I can do some wiring/voltage checking..
 

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Attached is the table from a 2001 Suburban. I've compared the numbers with a number of various schedules and factory recommendations. They all fall within 5-10% of the table so it is what I use on all of my r134a cars.

Good luck
 

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Discussion Starter #19
Thank you this chart pretty much duplicates the chart I had.. Unfortunately I increased the freon to the 50/219 readings and I still have the warm air coming out of the drivers side AC after about 3-4 minutes.. I am waiting for my factory Manual so I can do some further investigation about the mixing door and actuator for the drivers side..
Again Thank You,
 

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Discussion Starter #20
Hi, again, got my manual and the Freon pressures were very close to the ones listed earlier..I am still at a loss about the blend door causing the issue.. It is funny that the drivers side air is cold for about 3-4 minutes before getting warm. If the blend door was not functioning correctly I would not get cold air and then it gets warm. The air from the drivers side is cold but not as cold as the passengers side. Do you think the temperature sensors (I know know there are 6 of them) could be bad.. There are two on the drivers side and the cabin temperature sensor on the right of the steering column.. Or the A/C control module?
 
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