Thread: intermittent blower on heater

It's the ignition switch! Seems most try the easier route like I did as well of changing the blower motor resistor-didn't work. Most of the power for the accessories including the blower motor speeds and the wipers, goes through the ignition switch module in the column. When you turn the ignition to the on/run position without actually engaging the starter, you will know which accessories are controlled by the ignition module. The module is a small box with contacts in it with the wires coming from the accessories in the column and every time you turn the car on and off, these contacts will spark slightly if the high amperage draw accessories are not turned to the off position before starting and stopping the engine. After you change the ignition module in the column-to prevent another failure-make sure that you turn the blower off before stopping and starting the car. The small sparks cause the contacts to carbonize which eventually prevents the current from going through the contact. Eventually, the blower will stop working. Changing the ignition module swicth cost me $70 from GMpartsdirect.com/rockauto for the Delco and solved the problem-took about 2 hours and probably is not for a novice, but not too bad-work slow and carefully in the column and all will be good. The other option which I did do after I installed the new ignition module is to take the module apart ( a little tricky getting it back together with the springs inside and clean the contacts with light sand paper) and I saved the old GM one as a spare. The GP has 125,000 miles on it now and I did the exchange about 3 years ago-perfect since then. Hope that helps!