Auto Air Conditioning & Heater Repair: A/C, electric cooling fans, isuzu rodeo

Question
I have a 1998 Isuzu Rodeo with a 6 cylinder engine. It is a 4x2. I had an a/c transmission put in 3 years ago and it has worked great ever since. My problem is, when I am on the freeway or a long stretch it blows really cold, but in stop and go traffic it blows hot. What do you think the problem is?

Answer
If the vehicle has electric cooling fans for the radiator are they running when you are stopped ?. You could also have a problem with your DAMPER DOOR in the A/C duct work and it is not blocking off the heater core . You really need to have someone look at it. it is impossible for me to make an accurate diagnosis without having access to the vehicle.