Blower motor intermittant
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 42
Likes: 9
From: Texas
Blower motor intermittant
My '86 with 45k miles has never had the blower operate satisfactorily on low or medium speed. Up until recently it ran ok on high. Now, on cold starts the blower operates on high but will cut out when the engine is hot, so I have no heat or AC.
The AC compressor and system are on spec. I've already replaced the rotary switch, and the resistor bank under the hood. Before I replace the blower itself, are there relays or connections that I can check out first to resolve this nagging issue. If so, where are they located?
Jack
The AC compressor and system are on spec. I've already replaced the rotary switch, and the resistor bank under the hood. Before I replace the blower itself, are there relays or connections that I can check out first to resolve this nagging issue. If so, where are they located?
Jack
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
My '86 with 45k miles has never had the blower operate satisfactorily on low or medium speed. Up until recently it ran ok on high. Now, on cold starts the blower operates on high but will cut out when the engine is hot, so I have no heat or AC.
The AC compressor and system are on spec. I've already replaced the rotary switch, and the resistor bank under the hood. Before I replace the blower itself, are there relays or connections that I can check out first to resolve this nagging issue. If so, where are they located?
Jack
The AC compressor and system are on spec. I've already replaced the rotary switch, and the resistor bank under the hood. Before I replace the blower itself, are there relays or connections that I can check out first to resolve this nagging issue. If so, where are they located?
Jack
In Lo and the two medium speeds the voltage to power the Blower motor passes thru some resistors then thru the normally closed contacts of the Blower Motor relay. The AC fuse powers the Blower motor.
Unplug the connector going to the blower motor.
Turn the ignition On.
Set the switch to High and measure the voltage. The Black/Red wire is the voltage that powers the motor and the Black wire is ground G104 which is bolted to the driver side of the engine block.
If you measure battery voltage at the connector and the Blower motor doesn't run the motor is bad.
If you measure no voltage, set the switch to Lo or the two other medium speeds.
You should measure a different voltage at each speed.
Last edited by Hooked on Vettes; Oct 2, 2016 at 06:44 PM.
Instructor
Joined: Aug 2016
Posts: 209
Likes: 24
I had this same issue. I replaced my Blower Motor relay and that solved it. I also went ahead and did the resistor as well. If I remember correctly it was under $25 for both from Amazon. My blower works perfect now.
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 42
Likes: 9
From: Texas
I've just purchased a NOS blower motor relay on ebay, Part# GM 10019535. Can you tell me where it is located?
Jack
Instructor
Joined: Aug 2016
Posts: 209
Likes: 24
If you have already replaced the resistor then look between the resistor and the blower motor on the firewall and you will find the blower motor relay. At least that's where it was on my 86 manual HVAC not sure if they moved it for other years.
Thread Starter
Intermediate
Joined: Aug 2013
Posts: 42
Likes: 9
From: Texas
