Diagnosing A/C Problems ....

kruegs74 · Jun 30, 2007

ok tried my hardestand couldnt find it. best bet would be to call a dealership and hope the parts guy isnt and idiot. these kind of thing can be hard to look up. if all else fails go to a junk yard and pull one off. probably wouldnt even have to be off a mustang.

SeventyMach1 · Jun 30, 2007

Okay kool. Thanks man. I may go try tomorrow at the scrap yards if they are open.

BTW ... what program do you guys use? Is it All Data Pro? I have access to that .... and I saw NOTHING on it.

kruegs74 · Jun 30, 2007

no its fords own on line data base where i have acsess to all ford factory manuals, wiring diagrams, tsb's and all kids of stuff. they kinda frown on us sharing info but oh well. let me know if you got any more ?

SeventyMach1 · Jun 30, 2007

Awesome.

I just found one ... a whopping $2.32 part, lol.

http://store.lenzdist.com/product.php?xProd=315

EDIT: and thank you so much for that info. kruegs. I "thought" the inner valve was integral with the aluminum port ... but was not sure. I tried to remove it ... just wasn't happening. You just cleared that up for me. So now I KNOW for a fact that I need the whole aluminum port.

kruegs74 · Jun 30, 2007

seems a bit pricey might want shop around a bit
hope everyting works out

HISSIN50 · Jun 30, 2007

Justin, sorry about the R12 typo earlier. You were all over it.

Give these part numbers a shot:

Low = F3AZ19E762A $15.82
High = F3AZ19E762B $13.95

That is a direct quote from Methodical in post 17 of this thread.

Good luck.

SeventyMach1 · Jun 30, 2007

Thank you guys so much for helping a noob out. I think I got her fixed today. Ford was closed. O'Reilly's was the only place I could find it. They seem to always have the stuff I need in stock, never give out the wrong parts, and the staff at out local one is better than all the other general parts stores. They even have the correct IAC valve listed for our cars!!!

Anyway, I have cold air ... but maybe not cold enough, lol. I put 26 oz. in (2 cans) and 3 oz. of oil. IIRC, they are supposed to have like 34 oz. Is this why it's not as cold as it should be? I say this because on normal AC cars, even on a hot day, I will eventually have to cut the air down. I drove mine for 15-20 miles on the highway and felt comfortable ... but never wanted to turn it down. Lack of refrigerant?

EDIT: Np JT. And thank you for the part #'s. If Ford had been open, I would have used them. Will come in handy for any future searches.

HISSIN50 · Jul 1, 2007

SeventyMach1 said:
Thank you guys so much for helping a noob out. I think I got her fixed today. Ford was closed. O'Reilly's was the only place I could find it. They seem to always have the stuff I need in stock, never give out the wrong parts, and the staff at out local one is better than all the other general parts stores. They even have the correct IAC valve listed for our cars!!!

Anyway, I have cold air ... but maybe not cold enough, lol. I put 26 oz. in (2 cans) and 3 oz. of oil. IIRC, they are supposed to have like 34 oz. Is this why it's not as cold as it should be? I say this because on normal AC cars, even on a hot day, I will eventually have to cut the air down. I drove mine for 15-20 miles on the highway and felt comfortable ... but never wanted to turn it down. Lack of refrigerant?

EDIT: Np JT. And thank you for the part #'s. If Ford had been open, I would have used them. Will come in handy for any future searches.

Noob? Who's the noob? You're always helpin folks out.

That's neat that you got the ports from a parts store. If it's a common brand, can you post a brand and/or part number(s?) We dont have Advanced here (hence askin for a brand or part number) but I'm even having issues finding the ports from the dealership (for a non-outrageous rate).

For your AC itself, how often is your compressor cycling on and off? I use that observation as a crude barometer for how charged it is. If you are cycling every few seconds, that indicates that you might be down a little bit. Even if it stays on pretty long at idle (before disengaging), hold the RPM's up and watch the clutch. See how long it takes to disengage the clutch. Basically, when the compressor engages, the low side is pulled down till it hits the threshold of the LPCS, and the switch kicks the compressor off. The high and low side start back towards equilibrium until the clutch engages again (and the low side is then pulled down. The cycle is recursive).

Here's a pressure-temperature chart. Basically, the pressure you see depends upon ambient temps (if you drove out here and tested you car in 110*F, it would read differently).

Lastly, I highly recommend putting a small thermometer in your vent. That removes a lot of subjectivity (heat soaked interiors, you or I being about ready to melt, where even an industrial freezer would not cool us enough, etc). If you give us manifold gauge readings or even observational info about the cycling, along with vent temps, we might have some ideas.

Again, nice work Justin.

SeventyMach1 · Jul 1, 2007

Part # at O'reilly's for the high side service port is 59946. It is made by Murray. And costs $4.29. Has a 1 year warranty.

HISSIN50 · Jul 2, 2007

SeventyMach1 said:
Part # at O'reilly's for the high side service port is 59946. It is made by Murray. And costs $4.29. Has a 1 year warranty.

Thank you sir. Part number is filed away.
Having an alternate brand is cool.

Skidude69 · Aug 29, 2007

Good info here but can i ask a couple of related questions?

So at idle should the compressor shut off eventually? I have cold A/C but my compressor never seems to shut off at idle. Also should the high speed fan always come on with the A/C or just if the temp is high? Also it does this in MAX or norm A/C.

Thanks!

HISSIN50 said:
For your AC itself, how often is your compressor cycling on and off? I use that observation as a crude barometer for how charged it is. If you are cycling every few seconds, that indicates that you might be down a little bit. Even if it stays on pretty long at idle (before disengaging), hold the RPM's up and watch the clutch. See how long it takes to disengage the clutch. Basically, when the compressor engages, the low side is pulled down till it hits the threshold of the LPCS, and the switch kicks the compressor off. The high and low side start back towards equilibrium until the clutch engages again (and the low side is then pulled down. The cycle is recursive).

Here's a pressure-temperature chart. Basically, the pressure you see depends upon ambient temps (if you drove out here and tested you car in 110*F, it would read differently).

HISSIN50 · Aug 29, 2007

Skidude69 said:
Good info here but can i ask a couple of related questions?

So at idle should the compressor shut off eventually? I have cold A/C but my compressor never seems to shut off at idle. Also should the high speed fan always come on with the A/C or just if the temp is high? Also it does this in MAX or norm A/C.

Thanks!

As for how the compressor will cycle, that is a loaded question. The pressure in the system depends upon temperature. But the LPCS doesnt take that into account.

For moderate temps, if your compressor has 100% duty cycle at idle, it should not need a charge. YOu should find that if you rev it up to say 2K RPM and hold it, the compressor will cycle off within 30 seconds, stay off for some fraction of that, and cycle back on. That's about normal.

The high speed fan should come on anytime it's on Max AC. Mine never worked as it is supposed to, so I won't comment. I have read that MAX is the only AC function that triggers high, but that would be retarded. Arguably, MAX is easier on the cooling system than Normal AC (there's less heat rejection needed while recirculatng), so having high speed not come on with Norm would just be dumb. So I'm sure that's how it is.

Stanger007 · Aug 29, 2007

While we're on the subject, how does the information on this page look?

http://www.mustang-tech.org/wiki/94-95_Mustangs_Cooling_Air_Conditioning

Skidude69 · Aug 29, 2007

Yea, on my car the high speed fan doesn't come on until the high temp threshold is hit even with MAX AC running. Oh well, it doesn't overheat but it seems strange for it to not just stay on. Is that an issue with CCRM or just a fluke with the computer?

The wiki looks good!

HISSIN50 · Aug 30, 2007

Skidude69 said:
Yea, on my car the high speed fan doesn't come on until the high temp threshold is hit even with MAX AC running. Oh well, it doesn't overheat but it seems strange for it to not just stay on. Is that an issue with CCRM or just a fluke with the computer?

The wiki looks good!

I agree - nice addition Wes.

Skidude, yours is jacked. I'd crap my pants if the high speed fan didnt come on till ~226*F (I cant remember if you already have custom fan settings or if that's coming shortly).

Grab your meter. Turn the AC on max and ensure the compressor is engaged (it need not stay engaged, but we need to make sure 12 volts is reaching the compressor clutch for testing - this tells us the computer should know you have the AC on). Look at CCRM Pin 14 and CCRM Pin 17. See if 14 shows 12 volts. See if 17 shows continuity to ground.

If neither is true, I would *guess* that the driver failed in the computer. I had a similar type of failure on mine which is why I went with the stand-alone controller (I had a rewire in mind but the stock fan control sucked anyhow).

If neither speed is coming on, I have a work-around in mind. It's how I wire up the high speed fan circuit on cars with AC and two speed fans. It's kinda involved but it does work.

Good luck.

Skidude69 · Aug 30, 2007

I haven't had a chance to check the CCRM voltage but I did a KOEO test last week and the fan ran in both speeds, I am just pretty sure I haven't heard it go to high on MAX AC, I should be able to check and let ya know.

Thanks!
Jake

HISSIN50 · Aug 30, 2007

Jake, mine worked the same except the low speed fan only came with AC (ever). There's a differentiation in the PCM for testing the fan vs allowing high to come on naturally vs having it come on with AC (with the AC, there's hysteresis to keep the fan from cycling every time the compressor kicks off, etc).

Just so you dont think your symptoms don't make sense because the self test worked....................

Skidude69 · Aug 30, 2007

I looked through your old post..... WOW lots-O-info on this issue!

So I take it a new CCRM "may" fix the issue or I can buy another fan controller or the manual switch options?

Thanks!
Jake

Skidude69 · Aug 30, 2007

What is up with www.DcControl.com? it just has a email address and some forums listed only (Now Serving: and 4 forums)?

EDIT: I found Baskin's post. mimimun post count to order a unit?

HISSIN50 · Aug 31, 2007

Jake, I'd just PM Brian and let him you want his controller and see what he says. I won't put words in his mouth but I dont see why he would have any issue getting you a controller if you want one.

I think the post count thing was to keep people from joining the forum just to order a controller. If he wants, tell him to email JT. Because of your posts and our PM exchanges, I can vouch for you and the fact that this is not the case. Your join date speaks for itself too (you didn't join SN just to buy a controller. I think that's the biggie).

You've got it with the diagnostics. If you have Pins 14 and 17 reading what they should be, when they should be, and the fan isnt acting properly, then think CCRM. Otherwise, if the CCRM pins are not getting the proper trigger signals, that's not the CCRM's fault (the CCRM is just a box of 5 relays). That's where you look at the EDF module and PCM.

Here's a little supplementary fan relay info.

The manual switches are always an option.

I gotta say that I'm pretty poor so I dont get to spend money on the stangs like a lot of these guys do. But the Delta controller is one of the best investments I've made for the 94. If you have the coin, it's a sweet way to go. Using PWM, it makes our OEM fan control look quite antiquated. You install it and forget about it. If you order one, I recommend the LED and if you have the extra money, the rheostat it nice. This allows you to change your 'target temperature' from inside the cockpit. For example, I adjust it for summer vs winter temperatures, etc.

Diagnosing A/C Problems ....

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