No heat in 99 Grand Prix GT

whitmtob

No heat in 99 Grand Prix GT

Unread post by whitmtob » Wed Feb 03, 2010 2:27 pm

Had heat only coming from drivers side, replaced blend air actuator on pass side and had heat on both sides. Worked for about 1 month then yesterday my heat just stopped working. Only cold air blows out. Auto A/C , heat control seems to be working fine. Water Temp guage is not holding temp., it fluctuates, as soon as engine temp is reached it drops to below 160 then starts to climb back up. It's COLD and snowing, that's not a good combination when you have no heat or defrost.

3man6

Re: No heat in 99 Grand Prix GT

Unread post by 3man6 » Wed Feb 03, 2010 11:09 pm

Check the antifreeze level.
Does not sound like a control problem. but could try disconnect the battery for a few minutes toi reset the control head.
160 degrees should still give some heat though. Unless has an air pocket. Can't transfer heat from heater core if air in core.

swapem

No heat in 1999 Grand Prix GT

Unread post by swapem » Fri Oct 15, 2010 8:07 pm

Sounds to me like a simple faulty thermostat. Maybe it is opening too soon and opening all the way at once allowing the engine to cool down too quickly. You should still get heat with 160° coolant temperature though. If you never really get heat even though the coolant temperature is up to normal, and the coolant level is fine, and you are sure the blend doors in the dash all working fine, then you may have a plugged heater core. You can remove the hoses from under the hood and flush them out with a garden hose on full blast. Have both hoses disconnected from the engine but still connected to the heater core. Then run the hose full blast in one hose and let it run out the other then do it to the other does. You can also buy some flushing chemicals at your local parts store.

  • Similar Topics
    Replies
    Views
    Last post