2000 Pontiac Sunfire Engine overheats/surges in gear when n

  • 4 CYL
  • 2WD
  • 115,000 MILES
I am having issues when I am in gear but not moving. If I sit at a light too long (or at a couple lights in rush hour) the temp gauge starts to shoot up. Once I get moving again at a steady pace for about a mile or so, it seems to cool off again.

If I turn on the AC (it only works on full blast, all the other levels dont work at all), after about 5 minutes, it REALLY starts to overheat. Then it starts to rev the RMP while I am waiting at a light. Enough to where I have to keep my foot REALLY firmly on the brake or I will surge forward. Same deal though - once I turn off the AC and drive steady for about 1 or 2 miles, it cools down (according to the gauge) and drives normal.

My coolant level is good, and I have flushed it several times. The oil is good, as I have had 2 or 3 oil changes since this activity has been going on. The fact that the AC stimulates the problem is what has me baffled!
Do you
have the same problem?
Tuesday, August 11th, 2009 AT 1:17 AM

1 Reply

Thank you for the donation

Try replacing the thermostat for a start and make sure the cooling fans are coming on. If it continues to overheat get it block and pressure tested. The idle problem -clean out the idle air control valve and test the TPS and MAP sensors.

For the AC blowing at Hi only replace the blower motor resistor its job is to control the speed of the blower motor thru resistances in the circuit
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Tuesday, August 11th, 2009 AT 2:43 AM

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