I have a '07 Corolla CE. I have made no modifications to the original motor, transmission, etc. I have noticed that my heater is not nearly as strong as it was in the first few years of owning the car. Of the 4 available strengths that the heat blow normally the 1st one barely has any effect. Generally the 2nd is okay but not great. The only time it seems to be generally working okay is when I am on the highway and at a cruising speed of 60+mph. I have noticed the same thing in the summer when using my air conditioner though it seems to be even weaker. I usually have to use 3 if not the 4th highest setting of strength to get a comfortable feeling within the car. Though in the A/C's case it does seem that it is speed affected. What are the likely causes and fixes for this situation. If you happen to know what the price range of the fix would be as well it would be appreciated.
I have to agree with the last answer. However, to add to that, your A/C might be getting low on refrigerant too. Understand that A/C blows colder when the car is in motion than when it is just sitting. That is normal. If you notice the difference, it's likely, low refrigerant.
When only lower fan speeds are affected, but everything is fine on the highest setting, this is always a bad blower motor resistor. This is a low cost part, lookup online or call around for the best price. It is easy to get at and plug&play, a nice little DIY job. EDIT: A/C just works better at highway speed because more air is moving through front grill and the condenser. At a red light you must depend on a little radiator fan under the hood to remove heat from the refrigerant as it condenses. If at a red light you suddenly notice warm air from the vents or engine shuddering with the A/C on, then this indicates a problem with that fan or its circuit. If cold air returns when you speed up, it is definitely not low on r134-a, and adding more with a broken condenser fan will definitely damage the compressor.
Mark32937 answered it perfect! Your car probably has a low, medium, medium high and high setting for the speed of your blower motor. If any of these do not work then it's almost a guaranteed blower motor resistor. Very cheap and autozone offers a lifetime warrantee for them. But be careful installing, they are fragile. Secondly, like the others said, your A/C will always blow cooler when in motion. This is so because your condenser acts as a small radiator for your refrigerant. If theres no air flow to dissipate the heat from your condenser, the A/C won't be as cold. Hope this helps!
