I've got a 4.6 L '98 F150, and recently started to blow hot air out while running the AC, but when you switch it off and back on to AC, it will blow cold again. Sometimes will blow cold for awhile, then starts blowing hot air again. Could this be a Blend Door problem, opening and closing? Or is a relay or solenoid the problem by not kicking on?

 

Well, I narrowed it down to the blend door, the compressor kicks on, and the tubes are cold out of the accumulator (blows cold air), but when I turn the temperature control, it doesn't go to hot air. Cannot hear the door move. What things can I check, that controls the blend door. Like vacuum hoses??? Thanks for any input.

 

you need a can or 2 of juice. Take it in and have it checked or if your fairly competent buy a gunge set and do it yourself. It likely has a small leak and thats not uncommon for something that old to leak

 

Uh, no. He said the compressor engages and the lines get cold. That means it is NOT a refrigerant charge issue.


1. Check for a stripped temperature control ****.
2. Check for a failed Blend door actuator module.
3. Check for a broken blend door where the actuator mates with the door.

#3 is the most likely. It's also the biggest PITA to fix.

The temperature blend door is electrically controlled, it does not rely on vacuum.

 

You need to listen to the suggestions. I had that same exact issue and symptoms on my 1999 F-150 4.6 V8. Bought a Recharge bottle with Gauge at Autozone. It showed to be low. I followed the directions on the Recharge bottle and charged it back up. My AC works great now. It doesn't cost that much to try it.
If you find that it is something else, please post your fix so we can all benefit.

 

the blend door is infact a major pinta to fix. I did mine but because my heater core went out figured while I was in there. Similarly if you do the blend door might as well get a new heater core while your in there..

 

Fixed the problem, and it turned out to be a broken blend door. So I ended up going through HeaterTreater.net, and bought a new door. It wasn't too bad, but the instructions don't say that the new axle come in two pieces, so I tried for over an hour to install the door a one piece and it wouldn't fit. I called the dude from HeaterTreater.net, and said it comes apart, and I had it installed and working in 15 minutes. So if you have a blend door that is broken, go through this place, it's an all steel door and won't break. The one's from the auto places have a metal piece on the bottom, but plastic for the rest of the hinge. So it will fail again over time because of the hot and cold cycles the doors experience the entire time while the car is running.