a/c blows hot. compressor clutch is working. no codes for hvac. 90 psi static pressure idle pressure low 32 high 110. Tried adding Freon low side 32psi high side started climbing to about 150 then dropped below 100 then stabilized back at 110psi. Do I have a bad compressor on maybe slipping clutch. i have not checked orifice tube yet.

 

Testing instructions specific to a 1999 model year car

1. If the engine is at operating temperature, allow the engine to cool to room temperature.
2. Ensure that the ignition key is in the OFF position.
3. Connect an R-134a manifold gage set to the low side and high side service ports on the vehicle refrigerant system.
4. Check the low and high side pressures. The low and high side pressure readings should be almost equal to each other once the system has come to rest.4
Are both the low and high side pressures above the specified value >>>345 kPa (50 psi) © 20?
IF NOT (50 psi), then system is LOW...

Low System...
Are both the low and high side pressures below the specified value 69 kPa (10 psi)? If yes then,
1. Add 0.45 Kg (1 lb) of R-134a.
2. Leak test the refrigerant system. Refer to Leak Testing .
3. Repair the refrigerant leak.
4. Recheck the low and high side refrigerant pressures.
Are both the low and high side pressures above the specified value >>>345 kPa (50 psi) © 20?


1. Start the engine and allow the engine to idle.
2. Depress the mode control button until the UPPER position is displayed.
3. Turn the A/C ON by depressing the A/C button on the HVAC control head.
Does the compressor clutch engage?

1. Accurately measure and record both the ambient air humidity level and temperature. (These figures will be used later., see performance test table below)
2. The engine still idling in PARK.
3. Install a precision thermometer into the I/P center air outlet.
4. Set the HVAC control head to the following positions: • A/C button to ON
• Temperature control to full cold • Mode control button to UPPER (I/P outlets) • Blower speed to maximum high
5. Elevate and maintain the engine speed at 1000 RPM.
6. Allow the low and high side pressure readings to stabilize, if necessary
(Stabilization usually requires 2-3 minutes.)
7. Record the low and high side pressure readings.
8. Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart.

Do both the low and high side pressures fall within Zone A on the classification chart?
OR...
Do both the low and high side pressures fall within Zone B on the classification chart?
OR...
Do both the low and high side pressures fall within Zone C on the classification chart?
OR
Do both the low and high side pressures fall within Zone D on the classification chart?



1999 AC Chart

Depending on your results, zone A, B, C or D there are different troubleshooting procedure depending on zone...

Cheers,
Goose

 

I replaced orifice tube evac system and recharged with 134a. All works fine now 39 degrees out vent with normal pressures. Thanks.