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Discussion Starter #1
ok, 92 STS with the thermostat. A/C is out on the car, has a leak and needs to be fixed and re-filled. What Im finding out is that with no refrigrant in the A/C system the heat blows like crap. It's only blowing out from the foot area, not the top vents. Can this be fixed? Normal? Hate to sink alot of money into it fixing the A/C system for the sole purpose of using the heat properly
 

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It is normal for it to come out of the floor and defrost vents. You cannot make it blow through the main vents, which sucks IMO.
 

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White Diamond '03 DHS (with DTS floor shift)
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The A/C system has nothing to do with heat. Totaly seperate system.
 

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why does it tell me I have "very low refrigirant" and then "A/C compressor off" when I run the heat?

So your saying that no matter what the only air that comes out of the top vents will be A/C or regular vent air? All Heat comes out the bottom? THAT SUCKS !
 

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92_STS said:
why does it tell me I have "very low refrigirant" and then "A/C compressor off" when I run the heat?

So your saying that no matter what the only air that comes out of the top vents will be A/C or regular vent air? All Heat comes out the bottom? THAT SUCKS !
Yes, the climate control for your Cadillac is a split system which is to suggest that the heating cycle is totally independent of the cooling cycle. The common area is at and after the plenum. The plenum holds both the heater core and evaporator core which contains damper doors to block or distribute conditioned air to the cabin.

If the ECON button is selected with the warmer buttons the A/C compressor is turned off from the HVAC control module. This same system runs a check on the A/C system several times and reports any malfunction. The low refrigerant pressure is one such check. Once this code is set, the compressor will not energize until the code is reset, no matter how much pressure has been introduced to the system.

During the heating cycle it would be very objectionable, and dangerous for passengers in the front seating area to be blasted with hot dry air from the instrument panel ports. That is why hot air is distributed to the floor and/or windscreen where it will do the most good. Heat rises...remember? All GM cars are designed this way and have been since the late 1960's. Most other brands are as well.

Heated seat (option) is independant of the HVAC system. It is a grid installed below the upholstery and controlled by a thermostat and timer switches. The failure of your A/C system does not preclude the failure of your heated seat option. Heated seat failure can be tracked to grid, switch, harness, or fuse failure.
 

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Discussion Starter #6
if i remember correctly, the a/c leaks at the evaporator too, which makes sense why it throws that "problem error".

just seems like it takes a long time for your body to get warm in the car. When it only blows out the bottom.
 

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92_STS said:
if i remember correctly, the a/c leaks at the evaporator too, which makes sense why it throws that "problem error".

just seems like it takes a long time for your body to get warm in the car. When it only blows out the bottom.
Although it is possible for the evaporator core to leak, it is very unlikely. Many people are "told" by a trusted mechanic there is a leak in the evaporator and pay to have it replaced, when in reality, it is normally an "O" ring leak.

I worked for the Harrison Division of General Motors for 10 years and saw, first hand, the fabrication and tests each evaporator must endure. They were tested at 3X the normal operating pressure before they are assembled, then tested again, and again prior to final assembly. Then once again upon dealer pre-delivery. GM designed and manufactured automotive HVAC systems are the best in the world, hands down. Yes, they produce for other brand manufacturers as well.

Remember... you read this from a man who later owned a Lincoln Mercury dealership.
 

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White Diamond '03 DHS (with DTS floor shift)
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92_STS said:
why does it tell me I have "very low refrigirant" and then "A/C compressor off" when I run the heat?

So your saying that no matter what the only air that comes out of the top vents will be A/C or regular vent air? All Heat comes out the bottom? THAT SUCKS !
Most likely because you are requesting heat in the AUTO mode. In the AUTO mode the A/C compressor is enabled anytime the ambient air temp is above about 35 degrees. Use the ECON mode or A/C OFF (not sure how your car is configured) and you won't get the Low Refrigerent message.

At some point the Seville was given the MODE button wich allows you to choose the air distribution mode such as bi-level, vent, floor or floor and windshield. Obviously that must have come after '92.
 

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Discussion Starter #9
Ranger said:
Most likely because you are requesting heat in the AUTO mode. In the AUTO mode the A/C compressor is enabled anytime the ambient air temp is above about 35 degrees. Use the ECON mode or A/C OFF (not sure how your car is configured) and you won't get the Low Refrigerent message.

At some point the Seville was given the MODE button wich allows you to choose the air distribution mode such as bi-level, vent, floor or floor and windshield. Obviously that must have come after '92.
I dont have a mode button. Whats strange is I am requesting the heat in the ECON mode. I have the fan set on HI not HI AUTO
 

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Hmm, then maybe the LOW REFRIGERANT message must come on independently of whether the A/C is requested or not. At any rate, as Tex said the ACM commands where heat comes from and without the MODE button, heat comes from the floor and A/C comes from the vents. Sounds like it is operating as designed.
 

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The low refridgerant message comes on when the car goes through it's startup system check. Why would it be dangerous to blast hot air out of the vents? I have an 84 Buick park avenue, a 96 chevrolet s10 blazer, and I had an 88 Silverado that all blew heat out of the main vents, so it's not a GM thing. Dodge, Ford, and every GM I have ever seen all blow heat out of the vents. It really isn't all that bad because the car warms up so fast, but when my hands are cold I like to put them on a hot vent.
 
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