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2010 GT, AC compressor quick cycle and not cold.

5K views 19 replies 8 participants last post by  Dream_Mustang 
#1 ·
So yesterday I noticed my AC was rather lacking. Thinking it needed charging, I got a bottle of some R134A and a gauge. I filled it as directed, until it was in correct zone for the temp. It worked great last evening. I put maybe 2/3's of a can in. 15oz can.

I go to lunch today and it wasn't super cold, but I wasn't sweating so whatever. It was like 95F out anyways. On the way home, I get nothing. Straight hot air until about 3 miles down the road and I would get cold, warm, cold, warm etc.

I check it today and it's kinda on the low side so I grab a small can. I notice the compressor is short cycling when I pop the hood. I hook the second can up and follow the procedure. I pulled the trigger on the first cycle and right after it purges. Then it purges again.

From there I just watch the gauge. The compressor never cycles long enough to do anything, maybe 2-3 seconds at best. So I unhook it and drive it with the AC on. It purges about 5-6 times, then it finally stops purging. Now its back to the same old, hot air, cold air, hot air, cold air with the random few minutes of just nothing but hot air.

The fans are working, I can visually see the compressor kicking on and off. I'm using the low port, not the high port. No check engine lights. What am I missing?
 
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#2 ·
I don't know, but wanted to give you a reply anyway: I'm guessing maybe you have a leak.

My 2010 A/C is still working fine with no service needed yet, so I don't think there is any common issue and I don't know how that all works. I do live in New England where it doesn't get used that much so maybe that's why.
 
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#3 ·
Mine did work lol. I did find a solution tho. Partly my mistake and I guess the previous owner.

I remember when I first connected the freon hose (w/ gauge) the needle was pegged in the red when the compressor was off (that should have been the red flag).... Looking back, my system wasn't low it was too full. So after doing a little research I decided to pull some back out. Luckily I have a buddy that had the gauges and a way to capture it. I pulled out most of it, checked and then tested. Connecting the original freon gauge (as a baseline, to see if it was still pegging into the red) it was not. It was only about 70psi as opposed to 150+.

I started it up, and the compressor cycled like normal. No cold air, but it wasn't on and off constantly it was just on. I bought a third can of freon and started adding. This time the gauge was much lower than initially. Compressor on, it was 15-20psi, off it was 65-70. I filled it to about 25 on, 75 off and it got nice and cold.

Test drive and all is well again. I think it just had way too much the entire time. Me adding didn't help matters much lol. I think I need a tiny bit more, but for the time being I'm just going to leave it.
 
#4 ·
glad you got it figured out
 
#5 ·
Okay, problem is back.

It blows cold when the car is cold but once you are a few miles down the road or the car warms up it just stops working. Pressure seems fine, AC fan and cooling fans work. I have noticed it will stumbled quite a bit when the ac cycles on. RPM will dip to about 500 then come back up. And when actually driving, I can "feel" the compressor kick on.

Yesterday however, I let the car completely warm up and it worked great at idle. No stumbling, constant cold, no cold air, then hot, then cold. It just worked perfect. Today however, it worked at first but now it's acting up.

I'm thinking high pressure switch (I cant seem to find a diagram anywhere) or relay? Seems like it works great but something is flaking out electrically.

Evap and recharge entire system, check

Change the high pressure switch, check

Make sure both ports are running within spec pressure, check

And... It still quick cycles / works when it wants too. That's about $150 down the drain, although I can't say I'm surprised with how this car is going. Anything else I should be looking at? Hard to describe other than it works when it wants to, and when it does it works great. Other times it just quick cycles on and off rapidly (A/C compressor) or just doesn't work at all.
 
#6 ·
I had a similar problem one summer. It all of the sudden stopped blowing cold and the car overheated. I pulled over, shut it off and looked under the hood. Nothing obvious.
Started it up, A/C ran for a very short time then blew warm again and temp gauge went up again.
Turned out a relay sensor mounted on the fan shroud fried during all this. A/C ran off and on while the fan did the same thing till both stopped working completely.
On a side note and something else to look into, another 05-09 owner found a fried wire connection in the engine bay underneath a fuse box I believe.
Do a search on fan problems for our cars. It's late here. I'll try to look into it more this weekend.
 
#7 ·
Thanks, marylandGT. I've been kinda looking around for melted stuff, I think I might have seen the post you were referring too. I actually tried swapping the relay with the fuel pump relay as well just on a hunch, but its still acting up.

I'm thinking about attempting to replace the compressor coil and re-shim if necessary. Which I think that's about the only other thing I can replace or try. The fan kicks on yet the compressor doesn't, so that's kinda pointing me toward the coil and or shim.

I spun the pulley by hand and there was a little bit of drag, It didn't free wheel. I didn't use a feeler gauge on it, but the gap looked okay but I know that's not an accurate way of telling lol.

Okay, air gap was a no go. I popped the clutch off and there where 3 shims. I took the smallest one out and re-assembled. Worked great at first (as it usually does), and the clutch stayed disengaged when the A/C was off, and engaged with it on. Not 2 miles down the road, warm air. Turned around and it came and went the entire time. Hot, cold, hot, cold.

Parked it with it running and the compressor was doing the usual not coming on or just quick cycling. Gave the clutch a little tap with a breaker bar, nothing. Waited for the A/C fan to come on and tried tapping it again.... nothing.

So at this point I'm thinking it's not the air gap, I took about 0.008-0.010 out of it and it changed nothing. Low side pressure was 30psi when the A/C was on, so I'm kinda at a loss now. The only thing I have noticed is when the A/C does come on, the car almost wants to stall. Then it's like it quickly shuts off the compressor to keep it from stalling. Even when driving, you can feel a fairy moderate pull (almost like lifting off the gas at cruising speed) when the compressor engages.

Would any of this be visible to a scan tool? I'm almost thinking it's not even A/C related, possibly IACV?

Well one thing I can say is it's very consistent on a cold start. If I cold start on a hot day and turn the A/C on it works every time. Once the engine gets warm, it's a 50/50 shot if the A/C will work or not. It'll pop on and off, just stay off or just stay on.

Another random update, I found the Evap Temp Sensor under the dash. Pulled it, Ohmd it but couldn't get it to read the spec it should be at given the ambient temp. So I have one on order. I hope this works.

Evap temp sensor wasn't it.... Damn, I'm running out of options lol. I guess another evap / refill is in order or a compressor.
 
#8 ·
Older ac systems had orifice tubes, that also had a screen to catch any trash,,,, all I see for your model on NAPA is
Air Conditioning Filter Dryer, or Expansion valve.
 
#9 ·
Ford Motor Climate Control Problems
After re-reading this thread a few times and doing some research, I'm leaning towards JBerts response. You've got a leak.
This link I attached talks about leaks at the compressor.
It might be time to take it to a shop unless your willing to remove the compressor and check for leaks as mentioned in the link.
 
#10 ·
Ford Motor Climate Control Problems
After re-reading this thread a few times and doing some research, I'm leaning towards JBerts response. You've got a leak.
This link I attached talks about leaks at the compressor.
It might be time to take it to a shop unless your willing to remove the compressor and check for leaks as mentioned in the link.
I did some poking around with a UV light and didn't really see anything. In the car and under the hood etc. No leaks. Same pressure as before so it hasn't dropped since I last added it.

Here's what I'm thinking. It works 100% of the time when the engine is cold. Once it gets warmed up, it's off and on or just completely off. The only thing that really would react to temperature change would be the clutch coil. Cold it works fine, warmed up it's 50/50.

When it does work it works great tho. I can start the car at lunch break for example and it works great every single time. A few miles down the road, it acts up. Same things if you just sit at idle. After it warms up (not temp gauge, just under-hood temps in general) it kicks on and off.

Anyone know if its possible to pull the pulley off the compressor with it in the car? Radiator in the way?
 
#11 ·
Well, thinking outside the box. I drove the car all last week and Monday and Tuesday of this week. My battery died last Friday with no warning. Thinking maybe that had something to do with the A/C, I quickly replaced it with a new one and.... Same issue.

But the A/C is insanely consistent when cold. It varies when exactly it cuts out or starts acting up, but generally around the 5-10 mile mark (no WOT pulls, just normal driving) it acts up.

If there was a major leak or serious issue it wouldn't work at all. I had already replaced the High/Low pressure switch as well as the evap temp sensor and it did nothing. I checked it last week (low side pressure) and it was exactly the same as the last check.

So I was browsing ebay and a 2010 Radio / Climate control panel came across screen. I didn't know it was the entire unit, I figured it was broken up into sections but whatever. The really weird part is the fact I've had radio knob issues since the day I bought it. If you turn the volume or tune knobs too quickly, the volume will spike or just do nothing. You have to turn it very slowly to get it to do anything.

But seeing how it was an all in one unit (A/C heat, radio, all that in one) I'm thinking that alone might be the issue. Maybe its working until something gets hot (loose connection, high resistance?) then starts to act up?

Long story short, I bought it and it's being shipped here as I type this. Wish me luck.
777727
777728
 
#14 ·
Thank you. Worst case I'll fix my volume and tune knob only lol.

I wonder if the the clutch is beginning to wear out and slipping when it gets hot. Check out this recent video from Brian.
I actually did inspect the surfaces when I pulled the clutch off. I removed one small shim (very small, about 0.008 or so) which did nothing. I have no drag and it spins free when off. Another thing, It never has jerked or did any weird movements. Meaning it's either locked on and spinning or off. I've never seen it kinda spin or grab off and on like it was slipping.
 
#13 ·
I wonder if the the clutch is beginning to wear out and slipping when it gets hot. Check out this recent video from Brian.
 
#17 ·
Little update here. So I rented a vacuum and manifold gauge set. Vacuumed it down to 30in/hg and it held that vacuumed for about an hour. Added just a tiny bit of pag 46 (about a tea spoon) oil and 21oz of R134a. Everything went good, pressures were good and the compressor was cycling.

Test drive and... off and on at random. Same exact issue as before. At idle it would drop to about 500rpm when the compressor came on, then spike to about 1,200 when it realized it was about to stall and at the same time it switched the compressor back off. So, that wasn't it.

I might try the magnet for the clutch next.
 
#18 ·
Little update here. So I rented a vacuum and manifold gauge set. Vacuumed it down to 30in/hg and it held that vacuumed for about an hour. Added just a tiny bit of pag 46 (about a tea spoon) oil and 21oz of R134a. Everything went good, pressures were good and the compressor was cycling. Test drive and... off and on at random. Same exact issue as before. At idle it would drop to about 500rpm when the compressor came on, then spike to about 1,200 when it realized it was about to stall and at the same time it switched the compressor back off. So, that wasn't it. I might try the magnet for the clutch next.
Hey 02MustangGTGuy. just got a 2010 V6. i am also facing the same issue. wondering if you got your issue fixed.
 
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