strange A/C behavior

[Racincc85]

I've got a 1990 buick lesabre that i retrofitted to R134a. While sitting still idling, the temp at the vents in the dash is 47 degrees. when i start moving again, the temperature rises to 51 degrees. This seems to go against all logic, i would think the temp would drop due to the increased airflow through the condenser. what could be causing this to happen? thanks!!

[MagicRat]

Originally Posted by Racincc85

I've got a 1990 buick lesabre that i retrofitted to R134a. While sitting still idling, the temp at the vents in the dash is 47 degrees. when i start moving again, the temperature rises to 51 degrees. This seems to go against all logic, i would think the temp would drop due to the increased airflow through the condenser. what could be causing this to happen? thanks!!

My guess is that when you drive, you have more airflow moving through the dash vents and over the evaporator, so it warms up faster.

[bbpsingh]

I have buick lesabre'88.
I was getting 24, 63, and 65 codes.
What I did- Took out EGR valve, cleaned with carburetor cleaning spray. Then the codes gone away. Hower, the car has trouble in starting. It tries to start, starts with rough engine.
What is the proble?
Could you please advise any of you?
Bruce
[email protected]

[hoosier1]

Originally Posted by Racincc85

I've got a 1990 buick lesabre that i retrofitted to R134a. While sitting still idling, the temp at the vents in the dash is 47 degrees. when i start moving again, the temperature rises to 51 degrees. This seems to go against all logic, i would think the temp would drop due to the increased airflow through the condenser. what could be causing this to happen? thanks!!

This IS a POSER and here are some facts that may help you.
The ambient airflow through the condenser has little to do with the airflow through the evaporator (dash vents). The Expansion valve meters liquid refrigerant into the evaporator depending on the "superheat" setting of the expansion valve. The Expansion valve is
a thermostatic device and may be adjustable but do not attempt to adjust unless you are experienced and/or willing to accept the consequences. The valve senses the difference between the Evaporator inlet temp and the outlet temps and meters the liquid entering the evaporator.
The allen screw adjustment inside the outlet port outward to increase flow and inward to decrease flow- one turn equals 3 degrees of superheat. There are several different valve designs but they all work about the same. Only a skilled A/C Tech should do this.
The importance of this setting is to allow COMPLETE vaporization of the liquid into a vapor to prevent damage to the compressor. In other words the Correct Superheat setting will prevent any liquid from reaching the compressor. The Compressor is NOT designed to pump liquid- JUST GAS.
The proper Expansion valve setting is determined with gauges , a temperature chart and a Thermal probe.
If converting from R12 to R134A an adjustment keep in mind that R134 pressures on a 90 degree day will run about higher than with R12.
finally- be sure that your heater control vale is shutting off and not allowing any hot water into the heater core or a mixing door is out of whack and allowing warm air into the plenum.

[MagicRat]

Originally Posted by hoosier1

This IS a POSER and here are some facts that may help you.
The ambient airflow through the condenser has little to do with the airflow through the evaporator (dash vents). The Expansion valve meters liquid refrigerant into the evaporator depending on the "superheat" setting of the expansion valve. The Expansion valve is
a thermostatic device and may be adjustable but do not attempt to adjust unless you are experienced and/or willing to accept the consequences. The valve senses the difference between the Evaporator inlet temp and the outlet temps and meters the liquid entering the evaporator.
The allen screw adjustment inside the outlet port outward to increase flow and inward to decrease flow- one turn equals 3 degrees of superheat. There are several different valve designs but they all work about the same. Only a skilled A/C Tech should do this.
The importance of this setting is to allow COMPLETE vaporization of the liquid into a vapor to prevent damage to the compressor. In other words the Correct Superheat setting will prevent any liquid from reaching the compressor. The Compressor is NOT designed to pump liquid- JUST GAS.
The proper Expansion valve setting is determined with gauges , a temperature chart and a Thermal probe.
If converting from R12 to R134A an adjustment keep in mind that R134 pressures on a 90 degree day will run about higher than with R12.
finally- be sure that your heater control vale is shutting off and not allowing any hot water into the heater core or a mixing door is out of whack and allowing warm air into the plenum.

Very interesting. That may explain why my '88 Bonneville with R134a does not cool so well, and the compressor likes to cycle on and off every 10 seconds or so, when running.