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Discussion Starter · #1 ·
My A/C started acting up and i need help diagnosing it. here's what i know...

-i have owned the car for a few months and since i have owned it, i have always had to set the temp to about 85* to be comfortable. the actual temp was probably in the low 70's. not sure if this is related or not.

-everything seems to work except for the temperature of the air coming out of the vents. the driver side is luke warm. the passenger side is slightly colder than luke warm.

-the fan speed and active vents vary with the temperature selection, but the air temp doesnt follow

-compressor clutch engages and the appropriate freon line gets COLD

So i am thinking that either the computer that controls the flapper that directs the air over the heater core and/or evaporator is not working, or the flapper mechanism itself is frozen up.

Has anyone else run into this or have any insight before i start standing on my head under the dash and rip most of the dash out?

Thanks!
 

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2006 STS V8 1SF RWD
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what happens when you select 60 degrees? Do both sides get cold or just one?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Yeah, That ^^^^^

You might pull the little grille just to the left of the steering column (use a paper clip hook) and look down in the tunnel with a flashlight. That's the "aspirator" - cabin air temp sensor. There's a small computer fan down in there which runs 24/7 and it tends to clog the sensor with dust, slowing its response. Blow out the tunnel with a can of compressed "computer air". Careful - don't hit the small black bead in the tunnel - that's the thermistor (temp sensor) which sends a variable voltage aspirator signal to the HVAC system.

Look down in Discussions, Item Specific: Cadillac Tech Tips for further insight.............
 

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Discussion Starter · #6 ·
Displaying the Diagnostic Trouble Codes will point the way and prevent much guessing. Here's how to display:


Note and report all "B" codes and maybe someone here has been there done that.
will do! thanks for pointing me there!
 

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2006 XJ, 2000 Eldorado ESC--total loss :(
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Quick check of the a/c system performance:

Run engine and switch on ac. Wait a minute or two, look at the two lines going into the firewall. The smaller line is the inlet, the fat line is the outlet. On a functioning system, the inlet and outlet will be the same temperature (near freezing) or the outlet slightly colder. If the outlet is warmer than the inlet, you are low on refrigerant. Warmer temp on the driver side than passenger is indicative of this as well, though can't rule out blend door issues.

Your temperature dial offset sounds like a seriously clogged interior temp sensor. I'd definitely look at the aspirator mentioned previously.
 

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Discussion Starter · #8 ·
no B-codes.

ill check the freon lines closer. i have a bad feeling about that.

i did some more messing with it last night. some of my initial info was wrong. the temp will get hot if the temperature is set to 85 or above. the temp just has a minimum that is not cold enough.

its beginning to sound like a freon problem. ill check the lines and report back.

thanks for the help so far! all good info!
 

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Discussion Starter · #9 ·
it is a freon problem. niether of the lines get cold now. wherever the leak is it is pretty fast. it stopped working overnight.

now for the search...

just out of curiosity, how much pain is involved in changing the evaporator?
 

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2006 XJ, 2000 Eldorado ESC--total loss :(
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just out of curiosity, how much pain is involved in changing the evaporator?
Considerable... the dash will have to be removed for that job on your Seville.

But the evaps don't generally go bad on these cars (that I have heard of). Look for any oily & dirty residue around the compressor, any of the pipe connections, or the condenser. And please, whatever you do, no magic-in-a-bottle repairs to stop leaks. That stuff turns to epoxy inside the system and you will be looking at a total replacement!

What I would do, if it's that massive a leak, take it to a shop that can pressurize with nitrogen, then use soap bubbles to find the leak. Or, have someone recharge and add an ounce of UV dye (no other additives or conditioners). But if that's big a leak, it may not even hold a vacuum to recharge it.
 
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