2007 Pontiac Montana heater

Tiny
MONTANASUE
  • MEMBER
  • 2007 PONTIAC MONTANA
  • 3.9L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 315,000 MILES
When driving the heater works great, but stop or park the temperature drops to cold, continue driving heat comes back. I checked the level on antifreeze in the overflow and it was bang on
Sunday, November 9th, 2014 AT 5:28 PM

2 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It may be air in sys try replacing radiator cap. Also it may be losing voltage so check your belt and tensioner. Recommended replacement is 60 k. Also clean battery terminal ends
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Monday, November 10th, 2014 AT 7:35 AM
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
This happens a lot in GM front wheel drive cars. It can be a pain to bleed the air out of the system. This is exactly what happens in these cars when there is air in the system. Ok when the engine is cold take off the cap, make sure the radiator is full to the top, start the car and let reach normal operating temperature, now raise the rpm to 3500 and hold it there for 5 seconds then let it idle down, check coolant level, repeat these steps about 5 times. Check the level for a final time and put cap back on. Make sure you have heat at idle before turning the car off. Let the car cool down to room temperature and check level on the radiator again. Please do not look at the over flow bottle. That tells you nothing about the amount in the system. Top off the coolant and let it warm up to see if you have heat still at idle.
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Monday, November 10th, 2014 AT 4:03 PM

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