Blower - Direction needed

[98K1500Utah]

Getting a little cold outside, and my heater in my truck rocks! That thing is a blazing furnace - however, all of a sudden it is working intermittently. When it works, all speeds just work fine. When it doesn't, no speeds works... all of the other functions/buttons work (recirc / A/C). You can hear a quick light sound when you turn it on. I have noticed that good bumps or kicking the blower area or dash gets it up and running again, but next hard bump can take it out.

Is there areas notorious for this condition? Wiring? Resistor? Relay? etc.... where should I check first?

Thanks in advance -

 

[Eveready]

Getting a little cold outside, and my heater in my truck rocks! That thing is a blazing furnace - however, all of a sudden it is working intermittently. When it works, all speeds just work fine. When it doesn't, no speeds works... all of the other functions/buttons work (recirc / A/C). You can hear a quick light sound when you turn it on. I have noticed that good bumps or kicking the blower area or dash gets it up and running again, but next hard bump can take it out.

Is there areas notorious for this condition? Wiring? Resistor? Relay? etc.... where should I check first?

Thanks in advance -

My bet would be on a bad ground since it is intermittent. Other possibilities would include the control head. It would definitely be worthwhile to check all connections to the controller . Depending on what year it is those things can be notorious for connections that go bad or heat up. Check the connections behind the heater switch first and if that doesn't sort it out look for a bad or loose ground.

 

[thunderstruck]

Drop the glove box and look for connectors with a pair of red and black wires passing through them. See if the connection is burned.

 

[BarronTG]

Drop the glove box and look for connectors with a pair of red and black wires passing through them. See if the connection is burned.

Every OBS truck I've owned (5 to be exact) has had this issue, and it's always been this connector, which feeds power to the blower. It burns up after 20 years of high amp usage. Replacement off Amazon is about $28. Unless you're real lucky, the junk yard won't help, as they are burned up too! Part is ACDelco PT731

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[98K1500Utah]

Thanks for the info and the link to the part number - need to tear into this weekend hopefully.

 

[Eveready]

If you run the part number search on Ebay it comes up in several places quite a bit cheaper.