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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 1523
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Cadillac Deville: ,2001 cadi devilleAC blowing hot airService

Customer Question

Hello,2001 cadi deville
AC blowing hot air
Service AC System message appears
Happened when i was driving in some serious rain and driving thu
some water in the streets.
Checked codes current codes are:
DIM P1540
IPM B042
Submitted: 1 year ago.
Category: Cadillac
Expert:  Juan Crespo replied 1 year ago.
Hi there. Welcome to our site. Of the two codes you mention, only P1540 is valid; the second code is missing another digit (ex: B0423, B0428 or B0429). However, code P1540 does tell us that the A/C system was shutdown when a refrigerant overpressure condition was detected. Since this usually happens when the electric fans don't work, the first thing you should do is spray WD40 on the underhood fuse box to drive away any moisture; then remove and check the two 30A fuses marked Fan 1 and Fan 2 and make sure those are OK, put them back in and make sure there is current flowing through them (use a test light for this task); next remove the three fan relays and spray WD40 on the empty sockets, then put them back in. Next, find the pressure sensor on the hi-side pressure hose near the compressor; disconnect it and spray WD40 on both the sensor and the connector, then reconnect it. The last step would be to erase the codes, start the engine and turn on the A/C; fans should come on and A/C should cool. Kindly accept and rate my answer now if you think the information I've provided has helped you solve your issue. Otherwise, please reply. Best Regards.
Customer: replied 1 year ago.

Will do what you suggested. Also the second code

was B0429

Expert:  Juan Crespo replied 1 year ago.
Thanks for that added information. Code B0429 is usually caused by a bad rear control actuator and, unless water got to about a foot deep inside the vehicle, should not have anything to do with the A/C shutting down. Best Regards.
Expert:  Juan Crespo replied 1 year ago.
Hi again. Just checking to see if the information I provided helped you solve your issue. If it did, kindly accept and rate my answer now. If it didn't, please reply.
Best Regards.