A/C went out today.

Compressor is running Hi/Low pressures sides are hot/cold. A/C will start to blow somewhat cold when I turn on the car, but with in 45 seconds switch to hotter than ambient temperature. I think it's the Blend Door Actuator, there has also been mention online of a module (I assume a piece of electronics) that could be bad as well. Additionally, mention of an Evap Sensor, but since the compressor is running, I don't think it is this. I have also seen mentioned disconnecting the battery, what does this actually do? Why would it work?

Is there a way to diagnose which part is actually bad?

I went and stuck my head by the Blend door Actuator and had my girlfriend move from hot to cold. I can hear it move from hot to cold and back. Sounds like it flutters for a second then switches back to heat when switching between from cold to hot. It will also stay on cold for a little longer when moving from hot to cold on knob slowly. In the end it always goes back to the hot position for some reason.

I'm out in the yard right now and won't try to reply in detail. However, I've worked this very problem on my Grand Marquis and can tell you all the ins and outs. Probably going to be one of only two issues. If it's the blend door itself it can be a real PITA...inexpensive but a real bitch to get to. If not that, then it's probably the vacuum valve assembly and resolving that is simply a matter of changing a few o-rings and I'll send you a few of those.

In the meantime, there is a self-diagnostic code that tests for blend door movement. Hope you can find and run it.

edit: I forgot to say I'm not a mechanic. Let me know if you still want the info anyway.

This message has been edited. Last edited by: FRANKT,

2002 Grand Marquis. A/C was blowing hot. Mechanic checked it out before going away for weekend and said blend door actuator and $600 bucks due to taking apart the dash. Could fix next week when gets back.

Meanwhile, I googled around Ford forums and such and found something called EATC module reset (Electronic Automatic Temperature Control Module) - the heat/ac controls. I did the reset by pressing a few buttons in the proper sequence and it fixed itself.

About 1,500 miles later I had to replace the blower motor resistor on the firewall. All fine ever since - don't know if they were related.

The doors on his fusion are electronic, no vacuum stuff applies. It might take a shop with a good scanner or ford factory scanner to really tell you whats wrong, if it is in fact a motor or module problem. Simply touching the low and high side lines doesnt really tell you much. Some pressure gauges will tell a better story. Its tough to diagnose problems like that through the web.

quote:

Originally posted by Jaywendland1981:
The doors on his fusion are electronic, no vacuum stuff applies. It might take a shop with a good scanner or ford factory scanner to really tell you whats wrong, if it is in fact a motor or module problem. Simply touching the low and high side lines doesnt really tell you much. Some pressure gauges will tell a better story. Its tough to diagnose problems like that through the web.

If it was in fact a compressor problem, I can't understand why the actuator would switch from cool to heat. Does it work that way? Older cars would just blow air across coils that were not cold, leaving ambient temperature air coming out of it instead of hot air. I can't think of any reason it would switch to heat to indicate there was low coolant.

It could be switching to heat if the door motor is malfunctioning or the module is malfunctioning, if it is switching to heat. Is it a dual zone system? Different temp control for driver and passenger?

There is probably code in system.No check me lights. Go to autozone,Pep boys, someplace like that and have them pull the codes. Proced e from there.

Single zone, only one actuator under driver side.

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Would autozone ODBII pick up a code for Ford electronics, or would I need to bring to dealership?

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I hate to randomly change parts and pray, but the actuator is $34 for autozone brand, $50-60 OEM. 3 bolts, 10 minutes. I'm thinking it's worth a roll of dice vs $100+ to diagnose it.

The zone should be able to scan it. you're just looking for a OBDII trouble code.

No. The little bullshit obd scanner at autozone and the like wont pick up a code from an hvac module. Those are factory codes not obd2 codes. If you want to throw a part at it I'd stay away from auto zone unless the brand they are selling is a Dorman, motorcraft would be my first choice though.

Rock auto has both brands for less than auto zone.

https://www.rockauto.com/en/ca...+door+actuator,10721

quote:

Originally posted by Jaywendland1981:
No. The little bullshit obd scanner at autozone and the like wont pick up a code from an hvac module. Those are factory codes not obd2 codes. If you want to throw a part at it I'd stay away from auto zone unless the brand they are selling is a Dorman, motorcraft would be my first choice though.

It is Dorman brand. I think I'll pick one up and give it a shot since it's so easy and cheap to do so. Any validity to removing battery cable to allow the module reset itself? Is that worth resetting all my radio presets and clock? Or fake internet lore?

If you leave it disconnected long enough the module will reset and perform a door position relearn, it might work, it might not. You could also find the hvac fuse and pull it out for 10 minutes.

Fuse #15 in the fuse box on the driver side somewhere, either under the steering wheel or behind a piece of trim to the left of the steering wheel, between the dash and the door.

BTT. How did this turn out? All fixed?

Ford scanner to pull HVAC codes. I do three or four evap temp sensors every week at the shop.

a bad sensor wil set code B1B71:XX