Skip the auto shop - Our mechanics make house calls

Q: No A/C or heat and car is overheating

asked by on

At end of summer my AC started to blow warm n spurts- sometimes cold sometimes hot. If I turned the knob on dash from cold to hot back to cold it would start to blow cold again. When if started to get cooler at nite n past month I turned heat on & it was blowing cold so I played the knob game again to get heat but didn't work as well. Very random heat. I already new my egr valve plugged up & had an appt w my mechanic 2 fix that n a wk.during this wk it turned cold at night & n morn when I'd leave to go to work/school early the temp gauge would shoot up to red lined fairly qickly. Light would come on hang there mayb 10 seconds at most then gauge start to drop & light would go out & temp would straighten out. I fig was the thermostat going bad & staying closed then opening up & all going back to norm.called mechanic told him needed to add that to fix it list.. tried to open overflow (as there is no visible radiator on this car) & the cap won't come off- it's stripped.

My car has 308000 miles.
My car has an automatic transmission.

A: Hello. You may have two problems here. The ...

Hello. You may have two problems here. The engine temperature gauge behavior could be a thermostat going nuts as you describe. I would certainly check ground connections for the engine temperature sensor, and the engine-to-chassis connections in general. It may be a wiring issue.

It is possible you have a blown head gasket issue, but if so the temperature would not likely come back down very quickly at all. I would recommend having an overheating inspection completed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment and estimate for repairs. The erratic heater/AC behavior may be a malfunctioning HVAC control, or possibly a heater control valve that is sticking. Getting the engine temperature back to steady operation first will make the HVAC diagnosis much easier.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Is it my battery

If the car has overheated before replacing the thermostat, you could potentially have a blown head gasket. I would start by checking compression to be sure this is not the case. You can rent these at the local auto parts...

Q: Reduced engine power 2004 Grand Prix

Hello - you don't specific what code is causing the Check Engine light to illuminate (oxygen sensor problem), but a failure of the pre-catalytic converter O2 sensor could cause a Reduced Power experience. Failure of the O2 sensor can cause...

Q: Heating - A\c systems malfunction

The 1999 model year of the Intrepid has control system diagnostics for the manual HVAC system. Diagnostic codes that may be relevant to the problems you are describing may have been recorded and, if so, they are reported via the...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.