99 Expedition w/ auto climate control and rear air.

I at first thought I had the infamous blend door problem, but I am not so sure now. At first (few weeks ago) the system blew hot air for a day or two. After that all was fine, now the drivers vents blow COLD/COOL air and the passenger vents blow COOL/WARM air. Blows COLD and COOL when the engine is cool, blows COOL / Warm (not hot) when the engine is at operating temp. This is only for the 4 dash vents in the front. Rear works just fine, maybe not as cold as normal though. Any ideas? Does this sound like a charge issue? Looked at Vac lines and all seem fine, changing from hot to cold works just fine, so this leads me to think the blend door is fine. Appreciate any help you can provide.

Thanks!

 

Just a thaught, but maybe something is blocking, causing it to be both rather than one or the other. It's a biotch to disassemble the whole dash to find nothing or something small. That's a tough one really, because mine did not let in cold at all, so it was obvious the blend door was ****. Maybe it's open partial and stuck half way.

 

Only thing I know of that would be partially open or blocking, would be the blend door. I really do not think this is the problem as two dash vents blow cold/cool and two blow cool/worm air. I know of nothing that splits the air from passenger to drivers side. Turning to heat, makes all vents blow hot air, turn back to cool and you get two cold, two cool. Strange.

 

No kiddin', even how the rears work fine. I don't know, because even if the blend door (whatever it's called) is ****, the air temp won't change. Like mine failed in the winter, at full heat. By turning the ****, I don't think there was really any difference in temp. What about leaves or some other crap that may be in somewhere? I wish I knew where to find a venting schematic to locate certain things, like an exploded view of the dash etc. Only place may be factory shop manuals or a chilton book.

 

Yeah, I think I am going to have to break down and buy an online manual for it or something. I thought about foreign object blockage but its garaged all day and night, and the only animal I have that small enough (kitten) is still alive .

Anyone know what happens when you need a system recharge?

 

A system recharge usually means your air is slightly warmer. Do a check as follows:
- Warm engine to operating temp.
- Put air on coldest setting and fan full blast.
- open the doors to make sure the a/c thinks it's still hot so it will run constantly.
- After the system reaches operating temp, touch the 2 lines going to the evaporator at the firewall. The thinner tube going from condenser to evaporator should be cold. The larger going to the compressor should be colder than the thinner one by 3-10 degrees.
- If the evaporator outlet is considerably warmer than the inlet, the system needs a charge.

This info was provided by the Haynes manual for the f-150 and expy's 97-02.

Really though, if the a/c needs a charge, it would blow hot on hot and half assed cold through all vents not on one side or another. Try the test thaugh. Or have the dealer do a check, they charge you a bit for diagnoses but with that, finding my blend door at fault, the blend door motor a charge of a/c juice (top up) blah etc. $330 CDN out the door in a few hours so very worth it to me with a blend door problem. Yours has me ???, but like I said, do the test to see first. Oh ya, the outside temp should be fairly high, like 60 or 70, but definetly over 50. Good luck.