A/C help on a 94 MTX

[Brook24v]

Ok, I will try to explain this best I can, because it is a pretty odd ball deal.

For some time now my father’s 250k mile SHO has had A/C problems. Its not your typical issue though. The lines hold a perfect charge, the compressor works just fine, and everything else will work on a full moon when it decides to actually work. Here is the weird part – You can pull the car out of the garage, pop the sunroof, and the A/C will work perfectly. You can go for about 10 miles, close the sunroof, and the A/C will quit working. WHAT THE **** WOULD CAUSE THIS??? I assume the cabin pressure is messing something up, but I have no idea what. There are a few other really weird things that will cause the A/C to kick off, but I won’t bother trying to type them out. One thing I do know is that the A/C will pretty much be done for the day once it kicks off that first time, but it will sometimes kick on for a little bit again in the morning when you go to drive it….. till you open the windows or something.

So is there some kind of blend door or switch or something that could possibly get messed up with cabin pressure? I’m lost here. Any knowledge will help a lot! :type:

 

[Phoenix]

Damn that's a wierd one, keep us posted if you fix this....

 

[Brook24v]

Damn that's a weird one

Haha, I hear ya. This is going to require some ********* knowledge about how the A/C is controlled in a Taurus to figure this one out. ****, I was tapped out after I realized that it has a full charge......

 

[Brook24v]

Bump bump.

 

[93rev2sev]

If you're a parts hangin' guy like me, try a new IRCM. Just make sure you replace an "M" with an "M" and a "J" with a "J".

Heck, maybe the connector just needs a cleaning. It sounds like that to me when you mention that it works until the current on the circuit changes...reminds me of badly corroded(loose) battery cable...it'll start one minute and then nothing until you go wiggle the battery cable.

I think an electrical connector is the cause. To be sure, roll up your windows and start the A/C. Now, instead of lowering them...try to put them up even more. This will load the motor the same way as lowering the window but the cabin pressure won't change. If your A/C still kicks off...get some electrical contact cleaner and go to town.

 

[SeanMc]

Fuse?

 

[Brook24v]

If you're a parts hangin' guy like me, try a new IRCM. Just make sure you replace an "M" with an "M" and a "J" with a "J".

I'm a noob. What is IRCM.

I think an electrical connector is the cause. To be sure, roll up your windows and start the A/C. Now, instead of lowering them...try to put them up even more. This will load the motor the same way as lowering the window but the cabin pressure won't change. If your A/C still kicks off...get some electrical contact cleaner and go to town.

I forgot to mention that the A/C will still kick off eventually even if you don't mess with the windows or anything, it just takes a little longer to do so. Really odd ball deal, huh!

 

[Brook24v]

Ok, so I just got off the phone with my father, and he gave me some more bazaar details on this. Also, some of the information I have posted about this is incorrect. Read below for details:

1) You can, in fact, drive for quite some time without the A/C kicking off as long as you do NOT close the sunroof or windows. If you are to roll down a window or pop the sunroof, the A/C will kick off every time once the car is sealed back up. It is fine if you pop the sunroof or whatever, but you’re screwed once you go to close anything.

2) This A/C problem will act differently depending on the temperature outside. If it is hot outside, the climate control will never actually try to mix the cabin air, and the A/C will work just fine. On a cooler day, the cabin temp will start to reach the desired temp on the climate control and it will then start to slow down and mix or whatever. Once it does that, the A/C will quit.

Oh, and if you are wondering, I replaced the climate control with a newer hard button. This A/C problem was the same with both climate controls.

 

[93rev2sev]

Sounds more and more like a bad connection somewhere.

The IRCM is the 5 inch X 5 inch x 1 inch box bolted to the radiator support...near the drivers side. It has a large number of wires connected to it with a belt buckle lookin metal hold down thingy. It's probably under your emmisions sticker/sight-shield.

It controls oodles of stuff. From cooling fans to the rear defroster. If one of the connections to this controller is flaky, I can see how it might make wierd things like your A/C problems happen.

 

[Brook24v]

Is this that black box thingy that is under the plastic cover with the belt stickers that bolts to the support? Also, is a IRCM out of a 91 interchangeable with a 94 MTX? If so, I have a spare.

I might as well try to swap out IRCM's. At the very least it will eliminate that from being one of the problems so I can pin point it further.

 

[Brook24v]

Is this the IRCM???

Sorry for the engine picture jacking. I just Google'd till I found one without a plastic cover.

 

[SHOMON]

when it kicks off does it blow hot air? if so then search the forum for the climate control self test. My car gets a 2 every time blend door motor.But this also resets the climate control that way you can try to duplicate the cars symptoms at home. Also does it only do this with the fan in the auto setting? if thats the case when it happens put the blower on manual. It could also be the blower motor resistor the electronic board rusts up after a while
from the condensation in the heater box.

 

[Brook24v]

Is the BMR easy to get to?

 

[blownatx95]

yes it is under the passenger side of the dash, two 8mm bolts if i recall correctly

 

[Acidic]

Do the self test and check the clutch gap....

The only nightmare would be something wrong with the blend door or the evap.... everything else can be easily replaced once it's diagnosed...

 

[Brook24v]

The only nightmare would be something wrong with the blend door or the evap....

So dropping that damn dash might be in the near future? I still have a feeling there is something up with the blend door. Might as well replace the stupid heater core while we are in there. I'm sure it's days are numbered.

Will I find this if I just do a search on a "climate control self test"? I've never actually done this before. I learn something new every day.

 

[hawkeye18]

+1 on the self test. The procedure is on here somewhere, I gotta run but I'll post it once I get back tonight!

 

[I'll sho u]

put a jumper wire in the a\c pressure switch and see if it still quits. The pressure switches go bad quite often. Also does it act up only on automatic air or no mater where you set it? I have seen the ambient temperature sensor go bad (usually mounted in the dash somewhere) that will cause a problem when the climate control is set to automatic.

 

[Brook24v]

Thanks for your input, guys.

This weekend we went and drove the car around. We pulled out of the driveway with the AC on, and there wasn't any cold air blowing. We then popped the sunroof, and it started blowing cold. I'm really starting to think there is something screwy with that blend door. I don't get it.

 

[projectSHO89]

The blend door only controls the temperature of the outlet air, that is, the mixing of the heated and cooled air to provide the desired result.

If you are getting any other symptom than a temperature change of the outlet air, you need to describe it fully. Blend door faults on the Taurus (including the SHO) are usually characterized by a failure of the blend door actuator, not the blend door itself like on the F-series that breaks if you slam on the brakes or happen to sneeze wrong.

Instructions for the EATC self-test are in the FAQs at www.shotimes.com under "Care and feeding". BDA faults are usually characterized by "02" fault code. There are also two fuses that must supply stable power to to the BDA.

Again, you need to accurately characterize the failure. Typical descriptions would include:

1) A/C cuts out and the outlet air temp rises to around outside temp

2) Outlet air gets hot as if the heater were turned on

3) Outlet airflow switches to the wrong location

4) Output airflow changes speed dramatically or can't control speed

Get us the most accurate description of the fault and run your self-test.

Steve