B350 1 Ton Van V8-5.9L VIN Z (1992)
Evaporator Core: Technical Service Bulletins
A/C - Evaporator Freezes Up/Lack Of Cooling
NO.: 24-17-94
GROUP: Heater & A/C
DATE: Nov. 18, 1994
SUBJECT:
A/C Evaporator Freeze-Up or Lack of Cooling on Cycling Clutch A/C Systems
(Fixed Displacement Compressor)
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 24-17-92 DATED DEC. 14, 1992 WHICH SHOULD BE NOTED IN YOUR
FILES. THE REVISION CONSISTS OF ADDITIONAL MODELS. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS**.
MODELS:
DISCUSSION:
A loss of A/C airflow and/or cooling while the A/C blower fan continues to operate may be experienced on some of the above vehicles.
The electrical signal from the A/C cycling clutch switch passes through the Powertrain Control Module (PCM) to engage and disengage the A/C clutch
relay. If the PCM is not properly disengaging the A/C clutch via the relay, the compressor will stay on continuously and result in evaporator freeze-up.
Also, the PCM may not energize the A/C clutch relay at all. This condition results in the lack of cooling from the A/C system.
The PCM should be checked per the procedure in the appropriate Powertrain Diagnostic Procedure Manual. Diagnostic Trouble Code 33 (A/C clutch
relay circuit) will be present when either of these conditions are caused by the PCM. It is important to perform the complete test sequence because there
are other A/C clutch relay circuit components that could also cause or contribute to the condition.
POLICY: Information Only
