Heater Question

[RedRider]

A friend of mine has a 97 GMC Jimmy that's having heater problems.
She told me she's not getting heat. Could this be a vacuum issue? What should look for, and where should I look?

 

[slammedi'am]

Is the fan working and just blowing cold air?

Might be the ol heater core gone...

 

[Cowboy Cadillac]

Coolant level full? If the levels down coolant might not be getting to heater core.

 

[mr_bots]

Blend door?

 

[Bigredmariner]

Late 90's have been known to have issues with heater cores stopping up. Might check the hoses to see if it's getting hot water first. A garden hose usually will flush them out.

 

[Zembonez]

If it has water flow, I'd look into the blend door actuator. It should be vacuum operated in that truck IIRC. I don't think those were electric unless you had the auto temp option AC/Heater.

 

[davbell22602]

What about a heater switch/relay?

 

[RedRider]

Thanks guys. This gives me a place to start looking.

 

[That Crazy Squirrel]

Whatever you do, don't try to move the blend door by hand. If you do it will break and have to be replaced.

 

[drperry]

Also, check the transfer case vacuum switch.

Eventually it fails, and fluid starts creeping up the HVAC lines...