a/c working fine but approx every 10 mins the air blows hot for couple mins on 1997 Ford Explorer

heater switch only works a/c on full, not normal setting

Asked by for the 1997 Ford Explorer
Is it the A/C or the fan that only works at the high setting? in other words in the heat mode does the fan operate normally?
the fan works on all speeds. the a/c only works on "high" setting.could the problem be something to do with the hot/cold switch.checking to see if it is vacum or cable operated. thanks
1 more answer
it could be the resistor pack that controls the fan speed....try getting a repacement at a junk yard (aka recycle yard)