Running the AC compressor uses horsepower, and the truck does not have enough to overcome the loss.
the heater blows warm air when fan is on low but blows cold air when fan is turn to higher setting
To the best of my knowledge, there is no heater or outside air filter on the 1999 Ford Expedition, and Grease Monkey confirmed that when my Expedition (Eddie Bauer version) was in for service.
If the heater has a sweet smell it could be that the heater core is leaking engine coolant. When the leak gets worse you will have a wet floor on the passenger side and the windshield will fog up when you turn on the defroster.
did the heater core start leaking? anyway you should have no problem with the air if you bypass the heater core.
if youre trying to turn the heater on and cold air comes out, then its most likely the heater core
heater core, tough job.take it to a qualified auto technician
could need a tune up.
Heat control is by air flow control doors in the a/c and heater box. There is no water valve.
NO. Bypass the heater core by connecting the Inlet & Outlet hoses going to the heater core together. Do not plug either hose.
Of course, set the heater/air conditioner temperature control to cold.
it warms the air particles... witch then transfer the heat to you
Of course it affects the air conditioning,,,it also affects the heater. Any time u have a restricted air flow it affects how heater and air conditioning works, for the worse. Engineers have designed the heater/ac system to run on clean air, so therefore your heater/ac systems work faster and better with a clean filter. Not to mention your own physical health by breathing clean air.