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Discussion Starter · #1 · (Edited)
Does this look normal? I just evac'd and replaced the refrigerant. Exactly 21oz according to the hood sticker and manual. The compressor clutch never disengages unless I turn the A/C off. Then it disables the magnet and it spins free. Also, why does the compressor stay on all the time, but the gauge fluctuates? The gauges only drops and the A/C starts pumping when the fan comes on. When the fan is off, the compressor isn't compressing even tho the clutch is still engaged?


*That gauge was just used to check. I used a manifold gauge set to installed the refrigerant. And outside temps were 85F according to MSN.

And oddly enough, the A/C was actually pretty cold inside.
 

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Trying to diagnose AC issues via forums is really difficult. I highly recommend taking it to get serviced by a qualified reputable AC technician. With that said here are some good reads for you to learn about the system.

Here's the specs for the on/off pressures:
and everything you need to know on how the climate control system is suppose to operate:
and diagnostic procedures:

And some good DIY videos:
 

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Never saw a reply, but did get the thumbs up notification.
I re-watched the video with a set of headphones on. I can hear the fan cycling on/off while the compressor continues to run, which it shouldn't be, unless the high side pressure is reaching 240-310 psi according to the specs above for the dual function (high side) pressure switch. I believe the the low side gauge in the video drops pressure when the fan kicks on and begins to rise again when the fan kicks off. This makes sense since there is no air flow over the condenser coil causing the pressure to rise. There's definitely an issue because the fan shouldn't be cutting off at idle, unless its extremely hot and humid where you live and have the car parked. Other factors could be a clogged/failing orifice tube allowing the high side pressure to climb too high, and/or an over charged system. Again, its really difficult to diagnose AC issues via forums, because there are a few tests that need to be performed in order to diagnose it properly.
 
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Discussion Starter · #5 · (Edited)
It was 85 and not so humid out. The car wasn't even up to temp yet when I filled that. I checked the compressor clutch by hand (with it off) and then started it and took the video. So yeah, not even up to temp maybe 5 minutes of run time?

And yes, fan on = pressure drop. When the fan shuts off, the pressure rises.

Where is the orifice tube on a 2010? Is it under the dash? I can't seem to find anything on it.
 

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Discussion Starter · #6 ·
Just started it again dead cold. It's been sitting for about 24 hours. Started it up with no A/C on, and the fan was off. I turned the A/C on and the fan came on. It went back off. It cycled off and on about every 15 seconds.

When the fan was on, it starts to get really cold then the fan kicks off and its warm air. Then the fan kicks back on, starts to get cold again then back off after about 15 seconds. Very strange.
 

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Yep. Need to figure out why the fan is turning on/off. Do you have a set of manifold gauges? Need to get a reading of both hi and low pressures, specifically the high pressure when the fan turns off. According the docs I linked above the fan off pressure is 240-310 psi. If its not pressure related I would suspect the dual function switch or a weak high speed relay. I believe you can swap the low and and hi speed fan relays. If you swap them and the fan stays on with the AC turned on then that's more than likely your issue.
 

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Discussion Starter · #8 · (Edited)
I don't personally, but I can rent them again. I'll try to get a set tomorrow and see what's up. Ah, okay. That makes sense.

I'd be more than happy to grab a set of hi-low ran relays than replace the compressor lol.

And thanks, Jeremy. Your help (along with everyone else here) is very much appreciated.

EDIT:

Just swapped relay's. No change in on / off cycle but the A/C was cold the entire time. I let it warm up to temp and just sat in the car. Cold the entire time.

EDIT AGAIN:

Took it on a longer drive, about 20 miles round trip. A/C worked fantastic for about the first half. Then it was off and on.

When I got back I popped the hood and watched the compressor. I watched it for about 5 minutes and it eventually did shut off a few times. I'm gonna get the manifold set tomorrow... From what I see 20psi on the low side is way low. I'm wondering if I didn't put enough in. I put exactly 21oz in and maybe a tea spoon of PAG oil.
 

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Discussion Starter · #9 ·
So check this out. I got the manifold gauges and literally watched them for about an hour. The entire time it quick cycled, didn't work at all, worked perfect etc. This A/C literally just does what it wants when it wants.

So, when I picked up the gauge set I got another can of R134a a 12oz can. When I first checked it (when it was working) the low pressure was around 45 psi and the high side was around 250psi and the ambient temp was 90F. Very close to where I need to be so I added a little bit of R134a.

Here is where things get weird. After I add a little bit of R134a (I purged the line before opening the low side port, and then close everything off before checking the gauges) the low side pressure DROPPED about 3-4psi and the high side went up... I added a little more and ended up with 35psi and 270ish on the high side.

How does that make sense at all? Keep in mind, I already put in 21oz that Ford specified so if anything I'm a little bit overcharged. However, with it slightly overcharged the compressor seems to act more "normal"

And lastly, shutting it off and checking to see how quickly the gauges normalize. After about 30 minutes, very minimal change so I'm almost thinking it's the expansion valve. But... can I change the expansion valve without pulling the dash?
 

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Sounds like you may have found your issue if the 2 sides didn't equalize when the AC was turned off. I'm not sure if it's an expansion valve or TXV system, I believe its mounted on the firewall behind the intake manifold. If you watch the FordTeckMakuloco videos I linked above he goes thru both systems.
 
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Discussion Starter · #11 ·
I did, that video pointed me right to that. Ford wants like $278 but I found the expansion valve at o'reillys for $35. I'm assuming it's just an expansion valve, no electrical connectors at all.

I wish I would have known this before I did the heater hoses lol. I just had the intake manifold off a few weekend ago doing the metal heater hose assembly, both hoses on the firewall, water pump, t stat etc.
IMG_20210605_161057.jpg
 

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Discussion Starter · #12 ·
I ordered the new valve and it should be here tomorrow. I'm going to go the full on crazy route and try this with the intake on.... lol.

I managed to get the single 13mm nut off, pull the tubes and inspect the valve with my camera. It doesn't look bad, but... When I took it off after completely emptying the system there was still pressure when I loosened the 13mm nut. It wasn't a lot of pressure but it was noticeable. Not sure what means, but either way we'll see. I'm going to attempt with the intake on and if all else fails, I'll yank the intake again.

I'll update this when i get it on and charged.
 

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Discussion Starter · #13 · (Edited)
Can someone do me a solid and post a video of their 05-10 S197 doing a cold start and then turn the A/C on?

I'm just trying to see how other S197's fan systems reacts. I'm noticing on mine the fan never stays on for longer than like 15 seconds. So I'm not sure if that's normal or what.

Anyways, cold start ideally with a shot under the hood to hear the fan cycling. For reference, mine does 15 sec on, 15 sec off, etc on a cold start.
 

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The fan not staying on is not normal. The dual function switch controls the fan. Unless the high side pressure is getting up 240-310 psi it should continuously run on high speed regardless if the compressor is engaged.
 
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Okay, finally some promising results.

I swapped the expansion valve last Saturday and just now got around to doing the evap and recharge today. I did end up taking the intake back off to do the expansion valve. I didn't want to risk side loading or crushing the evaporator tube putting the expansion valve on. You have to install it by feel, so it's a 50/50 shot if you have the tubes seated or not. In my case, I got it. I couldn't find torque specs either, so that was also a wild guess lol. And I did use new seals front and back lubed with pag oil prior to install.

So, I sucked it down for about 10 minutes and then let it sit for about 5 to see if it held vacuum. It did. I charged it up (no pag oil, just R134a) and now the gauge isn't so spiritic. It's consistent on the low side at about 32-35psi and never goes above or below that. The high side gets to about 325psi and the fan kicks on (every time it hits 325, the fan instantly comes on) and stays on until lit gets to about 175-190psi then it shuts off. I watched this for about 45 minutes and it was dead on consistent.

I test drove and had A/C the entire time. I did some WOT pulls, turned it off and on a few times manually and it always came back on and stayed nice and cool. So I'm going to go drive it again in a little bit and maybe tomorrow if it doesn't rain and see how it goes. So far so good tho.
 

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Get a digital thermometer and stick it in one of the center vents and monitor how low the temp gets on max ac and max fan. Once the cabin gets cooled off it should maintain 35-40 +/- a few degrees. BTW, at WOT the pcm should trigger the compressor to shut off.
 

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Discussion Starter · #17 ·
I went for another drive and it was kind of acting up, not as bad as before but it was quick cycling. Yes, the WOT runs where to basically force it off and see if it came back on. I'm gonna hook it up again after work tomorrow and see what else I can find. Nothing is frozen up or leaking, but it got warm a few times but then ice cold. I wonder if I have the wrong hi/low pressure switch... 325psi seems kinda high for the fan to kick on? I would think it would come on alot sooner than that. It was about 90F when I charged it.

REPF504316 is the part number I used.

I'll do that tomorrow with the temp probe. I actually have one on my desk, not sure why I didn't use it.
 

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Still need to figure out what's going on with your cooling fan. Do you have a scanner you can use to monitor live data? If so, start the engine with no A/C and let it idle. The low speed speed fan relay should kick on around 190 degrees, unless you have a custom tune. The fan will kick on high speed at around 210 degrees. At idle you should not get to 210 unless its extremely hot. If the low speed kicks on at 190, turn on the A/C. When you turn on the A/C the fan should go immediately to high speed and NOT turn off unless the dual pressure switch senses high side pressure of 240~310.
 

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Discussion Starter · #20 ·
I might have an answer on the fan. So I took the cooling ran resistor off after doing some research. I've never heard the fan at any other speed other than full speed... So I think my resistor is bad. I took it off and checked for resistance.

Can anyone confirm the resistance across the non coiled piece? I see it's a $227 part.... So I kind of need to make sure.

I'm getting resistance across the coil, and two plugs out of the three male plugs, but nothing across that resistor.


781155
 
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