HT4100 4.1, 4.5, 4.9 Discussion, Blower motor not operating in Cadillac Engine Technical Discussion; Folks,
Wanted to do some diagnosis tonight but it's raining (no garage!). Service manual flowchart asks you to first determine ...
Wanted to do some diagnosis tonight but it's raining (no garage!). Service manual flowchart asks you to first determine whether the compressor or the blower doesn't operate (engine on, 60 degrees HI selected).
My question is, my blower doesn't operate in ECON with the heat turned up, either -- so doesn't that automatically mean there's some blower motor problem, OR is there some compressor interface that makes it a test variable?
This just started today out of the blue. Maybe just a fuse...?
Check for power at the power module - wiggle the connector with the blower turned on first, it may start up. I've seen poor terminal tension due to the high current draw over time. Don't guess, put a test light to it.
Im my experience the fan module dies more often that the blower motor. Just beacuse the AC clutch part of the module is still working that doesn't guarantee that the blower motor driver is not toasted.
I don't have the wiring diagram handy but you should be able to power up the blower motor directly to see if it'll run. Or at least use the test light (like cadillac_tech) mentioned to determine what is going on.
The A/C compressor and HVAC blower are on separate circuits. The blower will run in ECON even if the A/C is completely non functional. Follow Peteski's and cadillac_tech's advice - trace backward - test lights are cheap.
I can't recall the name of the part; something like heater/blower control module, but it's directly above the heater blower motor on the firewall with a few wires going into it. That is the likely culprit.