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.

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 1,000 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
  1. Home
  2. Questions
  3. No A/C or heat and car is overheating

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: Heater pipe broke water run out now car does not start

If you broke a coolant or heater hose or pipe and then continued to drive the vehicle until the engine seized up then you may have damaged the engine bearings, pistons and other major components in the engine. If the...

Q: It has a service engine soon light and i dont know what it means?

The service engine soon light inspection would be needed by a mechanic like one from YourMechanic to find out why the light came on. The light is only and indicator that the computer in the car has detected a problem...

Q: DPF (Diesel Particulate Filter) melted

Hello. The DPF functions by trapping certain diesel particulates, and periodically goes through a regenerative cycle to burn those particulates (i.e. when you're on the motorway and get the temperature high enough to regenerate). This is a bit speculative, but...

Related articles

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.