Recently when I activate the heating/cooling system the recirculation and AC light blink for about 20 seconds. According to the manual this means a fault in the system has been detected. Also, recently I've noticed when I put the heat on the air isn't that hot. Any ideas on what the problem might be?

 

The temp blend door motor might be bad or out of Adjustment.
That would make the lights flash as well.

 

If the thermostsat was bad would that cause a fault in the detection system? Also, would a bad thermostsat cause the air to not be as hot?

 

It would not cause the lights to flash.
Might cause the air to be cool.

 

A thermostat that is stuck open (one that's too cold for the application) is usually the cause. It is also possible that an air pocket in the heater hose/heater core may be interfering with coolant flow through the heater core.

 

Hi, I am a new member and I just found a car for a friend on Ebay. My friend bought a 98 S70 and she is getting an intermitant problem with the heater. She sometimes gets heat only from far right or left side vents but center vents are cold. Do you have an idea of what that might be or could it be the heat blend motor or something. I will have other issues to meantion later, thanks, Rick
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The blend door motors might need to be recalibrated.