[Alinco] Thermal problem DR-635

[Ray]

I have a DR-635 installed in my car.  It has worked fine during the warm 
weather but now that it is turning cool in the mornings at 50 degrees or 
less, the receiver stops working and a loud white noise comes thru the 
speaker.  The volume control has no affect on the level of the noise.

The transmitter still seems to work as it will key up a repeater and the 
S meter will display it, but no repeater audio comes thru.  I suspect 
the problem is in the audio amplifier section.

If left on with the car heater warming it up for about 10 to 15 minutes, 
it will return to normal operation.

Has anyone any experience with a like problem, which might be helpful in 
resolving it?

Your attention is appreciated.
Ray, W4BYG