Jim Grant's Tech Tips
'95 Chevy K1500, High Speed Only Blower Fan
Q: I have a 95 Chevy
K1500 that recently had all but the top speed of the AC/Heater fan quit.
Here is what I have tried: new switch, two new relays (1 under the hood
and 1 above the glove box), and a new blower motor. Nothing has changed,
works on top speed only. Any ideas?"
With the work youve preformed and the description of the problem,
its a good indication that you may have a failed blower resistor.
When you select blower speeds at the dash control you are, in reality,
directing electricity through different resistors. Each resistor has a
different value so it only lets a certain amount of electrical power travel
to the blower motor. On the high speed fan setting all of the resistors
are bypassed to allow for full electrical power to the blower motor. Because
you have high speed, we then know that the blower motor, relay, A/C control
module and fan switch are operational. If any of those components were
not operating correctly, you would not have high speed blower operation.
You should also know that ALLDATA Information Systems has a Technical
Service Bulletin (TSB) showing an updated part number for the blower resistor.
This TSB was issued some time ago, so it is likely that the new resistor
you buy will be the improved part number.