Cadillac Owners Forum banner

1 - 6 of 6 Posts

·
Registered
1990 DeVille
Joined
·
181 Posts
Discussion Starter #1
In this '90, the blower was stuck in the HIGH position, even with the ignition off. I discovered that the blower control module (center of firewall, with two connectors to it and three screws holding it into the blower air path) had failed. Pulling either connector stops the fan. Fixing it, however, is another story. There are two solutions:

1. Buy a replacement: $150 for a new one, $40-70 for a used one - and "used" is a crapshoot.

2. Build a replacement. I bolted a 3 ohm 20W power resistor to the existing heat sink, and ran the power through it (RED to PURPLE). I then added a switch to the circuit, under the dash. Works fine, but one must remember to turn off the switch.

I may later make this a bit more automated, with the ignition switch activating a relay, and a 2- or 3- position switch to resistors of different values.
 

Attachments

·
Registered
1992 Sedan Deville, 1984 Lincoln Town Car
Joined
·
759 Posts
Brilliant, Watson. I hope this is not patented, I may need it soon since my blower doesn't work at all. I'm hoping it is because the Freon is gone, tho and not the power module.
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
87,116 Posts
Freon charge does not affect the blower. It will disable the compressor, but that's all.
 

·
Registered
1990 DeVille
Joined
·
181 Posts
Discussion Starter #5
For those interested in this sort of problem... please help me build a little knowledge base with some simple tests.

1. Disconnect your power module (two connectors).
2. With those leads disconnected, measure the resistance between the PURPLE lead and chassis ground - that's the DC resistance of the motor windings.
3. Reconnect.
4. With the hood UP, the engine OFF, and the ignition ON, use the climate control to set the blower speed to max. You can reach the control through the window while your head is close to the blower motor. Listening carefully, turn it OFF. Estimate the number of seconds it takes for the blower to wind down.
 
1 - 6 of 6 Posts
Top