1990 Buick Le Sabre - Blower Problem

[Goose]

Customer came in with an inoperative blower motor.

This car has automatic temperature control. I replced the blower module and all was fine for the first 5 minutes. Turned the key off and the blower continued to run. Checked the voltages and all seemed fine so I got another module and installed it. Two days later the customer calls and informs me that the blower motor runs all the time. Purchased a used temp dash control and installed it with another new module. All seemed good until I shut the car off and the blower continues to run. Voltage to the gray control wire is 9.1 volts instead of the 6 to 8 called for with both dash controls. All wiring appears ok. This is a fairly simple circuit with only four wire at the module. Power, ground, blower output and blower control.

The modules have all been brand new Delco modules. I am at a loss as to what to do next. Any ideas? Has anyone run into a simular problem or had trouble with the Delco modules?

I am about ready to blow a gasket!

[ricmorin]

No issues with Delco modules. Curious, though. How much draw is the blower motor taking? It could be damaging those modules.

[fortknoxx]

are you the first person to fix this problem? is there any evidence that someone else attempted to maybe replace the blower motor? if so grill the customer on what was done. they could have had their cat fluffy fixing last week.

[brianp87]

I have seen blowers create too much resistance and damage resistors

[Goose]

When the car came in it had a switch wired in to by-pass the module. The wire was too small and he almost started the car on fire. I have not tested the current draw on the blower motor but will do so. As i recall it should draw no more than 10 amps. Does that sound about right? Thanks for the input. I will post a solution when I find it.

[steven kiser]

on old type mechanical relay styles the amp draw may cause the relay to stick. i personally haven't seen it with the modules. not saying it couldn't happen though. on the other hand i've run into melted connectors and loose grounds. is the blower the only issue? are there any other accessories staying on? look at the lead for the module closely for melting. was there anything added recently such as a remote starter or a stereo? what speed is the blower stuck on? if i remember correctly,on some g.m. applications the blower will always circulate. some don't even have an off position.

[ricmorin]

When the car came in it had a switch wired in to by-pass the module. The wire was too small and he almost started the car on fire. I have not tested the current draw on the blower motor but will do so. As i recall it should draw no more than 10 amps. Does that sound about right? Thanks for the input. I will post a solution when I find it.

That's about right. Even 15 amps is ok, but no more. I suspect the blower is bad.

[Goose]

Sorry it took so long to post a fix to this problem. I checked the amperage draw and it was 20 amps. Replaced the blower motor and module. All is fine now

[steven kiser]

replacing the blower probably wasn't necessary but i've done the same thing on occasion. the resistor was probably shorted internally causing the over load. hope you took a good look at the plug for the resistor. i could fill a trash can with the ones i've replaced because they've melted inside. if there is any discoloring where they are flush with the face of the terminal i replace them. it's no more than a tome bomb. if the connector isn't as tight as possible it will cause it to overheat and melt even more than it is, eventually causing it to fail again. i can't begin to tell you how many terminals i've seen melted into a blob at the resistor or blower and they had been replaced recently at another shop.

[ricmorin]

Thanks for posting the fix. We had a feeling the blower was to blame. Did you happen to measure the amperage of the new blower?

A good policy is to measure the blower draw ANY time a resistor goes bad. I'm getting better at that but still let a few get through. Diligence!!

[Goose]

Steve....In all due respect the module is the resistor as this car has automatic temp control. The new motor rus drawing 10 amps when it wired direct to power. Funny thing was I had full speed from the old motor and it sounded fine. I will never make this mistake again. Thanks for all the input.

[steven kiser]

oh, i thought you were talking about the double plug module / resistor that attached to the top of the heater box next to the blower motor. when those were commonly coming into my shop the smaller plug would always be melted and the larger primary one would on occasion me a bit distorted. my memory must be getting a bit hazy. where exactly is the one you're talking about?

[Goose]

This module is also under the hood in the heater box.

[steven kiser]

mmmmmm, must be talking about the same module but at different angles. my shop is within 1/2 a mile of a few g.m. dealers so possibly i saw more and it just upped the chances of melted plugs. i could be wrong but i seem to remember prying crusty connectors off the module / resistor.