Blower motor runs intermittently. Seems most affected by extreme inside the vehicle after sitting in the sun and by direct sunlight. If i park in the shade for a while the blower motor works more often. Funny thing is if i put on ‘heat’ it seems to run more often as well. Very strange. Resistor was replaced about 4 years ago when blower kept running even after i shut the car off and when the car was running the resistor ran only on high. That is not the case now. Is what I describe another function of the resistor? I’m thinking it’s a different problem.
You might need a new blower motor or there could be a problem with the wiring, including the connectors. Turn in the blower and try wiggling the wires. If the running condition changes, you may have found the issue. The car is 18 years old, and connectors, wire breaks, or wire shorts are possible.
The next time the blower doesn’t work, set the speed to high, reach under the passenger side of the dash, and with the handle of a screwdriver rap on the blower motor.
If the blower starts working, replace the blower motor.
There is a bad connection to power somewhere. The relay may be the culprit this time, the motor itself, or a connection to it.
Motor is new. Must be in the wiring. Thanks for feedback everyone.
Could be the blower resistor pack
Melted blower resistor pigtail . . . this is very common on GM vehicles of this era
There is no blower resistor in your HVAC system.
So forget that.
The problem is either with HVAC control module, or the blower motor control processor.
Thanks to @Tester for the diagram. The diagram shows there is no relay used in this circuit also. Check the voltages on the top part of the shown Blower Motor Control Processor while the problem is occurring. You should see battery voltage on pin B. Pin C should have less than full battery voltage on it (depending on the speed selector position) and pin A should have close to zero volts on it.
Up until recently I have been using blower motors from the salvage yard. Twice in the past four years. Second time I replaced the pigtail because it was fried. When the new motor was recently installed I replaced the pigtail again because the pigtail was fried again. What you say is making sense but something keeps cooking that plug. I’m thinking the resistor that was replaced four years ago may not have been a quality part. I live in FL. Would be nice to have AC all the time and not just part of the time. Funny thing is when it starts it’s intermittent process and i put it on heat, it will continue to run but who needs heat when it’s 95 in the shade. I have thought about just replacing the resistor again but I thought that was only a speed control part. I will share all info with my mechanic. It’s good to narrow down the problem before the trail and error process of a mechanic. Thanks everyone. … [yes the car is 18 years old but only has 130k and the rest of the vehicle is in good to excellent condition. It rides so smooth.]
The blower motor may be drawing more current than it normally should. That could cause the damage to the connectors. Have the current draw for the motor checked. Also, once damage happens like that it is best to replace both sides of the connection. The connections on the blower side may now have extra resistance added to them and that is causing the problem. If the connections are discolored that would be a sure sign of trouble.