Having a heat problem.

[yellow77]

Under normal conditions, the heater will blow warm air, and the temp gage sits around 180 degrees. Then every now and then, the heater will start to blow cold air and the temp gage starts to climb. this will go on for a while, when suddenly, the heater will blow warm air again and the temp drops back to 180 degrees. The thermostat is new, the fan moves a lot of air (flex blade), the water pump is newish I think, the hot water valve in the heater plumbing works.
Any suggestions, this is driving me nuts.

Cheers

Richard

 

[jdp6000]

Do you have A/C? is it possible that you cycling from heat to A/C. the A/C system drws a lot and does cause temp rise.

jim

 

[bill81vette]

It sounds like you have an air pocket in your cooling system.


bill.........

 

[Bob Chadwick]

It sounds like you have an air pocket in your cooling system.


bill.........

I'm with Bill.

 

[JohnZ]

Classic symptoms of a bad thermostat - instead of cycling smoothly to modulate coolant flow in response to coolant temperature, it's binding or sticking, then breaking loose. Get a Robertshaw #330-180 or the same thing re-packaged and sold by Mr. Gasket, instead of the generic parts-store thermostats.