Air conditioning experts in here please

[SVT CAMR]

Well I'm going to roll the dice! I ordered a replacement pulley from FORD.
I replaced the idler pulley last week and had another from many years ago. I started swapping them out to make sure it was not them. I also swapped in another alternator I had. It has to be the compressor.

I removed the compressor pulley too. But there did not seem to be any signs of wear or problems. I think it has to have the belt tension to reveal itself. I'm going to go for it. Letch know tomorrow at lunch time if I win or lose.

I normally don't guess but I'm worn out with this thing right now. My gut says to go with the compressor pulley. I will be sure to post the ford part number tomorrow too.

 

[laddanator]

Lad, if it was a bad compressor how would I know? What would or would not be happening?

I don't want to out smart myself here with a $100 clutch kit change.

Earlier in the day yesterday it started out as a squeal only when giving it some gas. Then it got louder. so I walked away and later in the day it was sounding worse. So what the heck I put the AC on and it sounded like rocks in there when the clutch engages. (maybe loose ball bearings?) Do you think it is just the bearing? I would rather not change the whole thing. BTW I think rock auto sells that bearing. Also I found a compressor on craigslist right out of a 98 cobra and it has 20K on it but was removed from the car 7 years ago and stored in a finished basement. The one I have was stored in the attic for 13 years.

What would you do buy the craigslist one $80 and swap parts or just buy new kit $115.

This is bullshit! I was in the middle of my celebration and then I could not even drive the car. :fm:

Well I'm going to roll the dice! I ordered a replacement pulley from FORD.
I replaced the idler pulley last week and had another from many years ago. I started swapping them out to make sure it was not them. I also swapped in another alternator I had. It has to be the compressor.

I removed the compressor pulley too. But there did not seem to be any signs of wear or problems. I think it has to have the belt tension to reveal itself. I'm going to go for it. Letch know tomorrow at lunch time if I win or lose.

I normally don't guess but I'm worn out with this thing right now. My gut says to go with the compressor pulley. I will be sure to post the ford part number tomorrow too.

Honestly, A/C problems on these cars make me more mad than just about anything else. You pull vacuum, let it set over night, vacuum holds, put freon in, week later, all leaked out!!! This has been my luck the last few times.

Man to be honest, I had 50/50 luck with rebuild kits. I know how much the A/C system stresses me out so I normally just replace the entire compressor.

 

[laddanator]

DSG makes a good point - the oil capacity spec is for the entire system. Your accumulator and heat exchangers will collect a huge majority of the lube oil. The general rule of thumb when it comes to servicing individual components is to replace only the amount of oil drained from the system (and the serviced components) plus an ounce or so with the understanding that you aren't realistically going to get ALL the oil out of them. If you simply replaced some o rings, lost a little oil in the process and refilled the system with the capacity spec - you are most certainly overfilled with oil.

Furthermore, if you added all of your oil to the compressor you need to turn it by hand a few times before you run the engine to confirm it won't hydrolock.

Too much lube oil is a bad thing. It negatively affects the performance and it could result in catastrophic failure because liquid cannot be compressed. Adding refer to the high or the low side is rarely an issue because it's all a vapor at normal static pressures.

DO NOT, under ANY circumstances use ANYTHING other than pure, unadulterated (no conditioners, sealers, improvers) R134a. The leak sealers in almost any brand of refer are horribly hazardous to ALL A/C servicing equipment. I have a $100 kit I use to test for these sealers and I send any job with this crap in their system down the road. It's garbage and it will contaminate every piece of equipment that ever touches your vehicle.

In regards to how to get the proper charge.....

Using cans from a part store is a guess. 1) you won't get all the refer out of all the cans unless you heat them, which is dangerous and 2) almost all the cans they sell have the garbage you don't want in them. If you have a gauge set, you can just keep charging it until your static pressures are equal to ambient temperatures. A fully charged R134a system will have static pressures of about 75psi in a 75 degree environment. Slightly undercharging will give you colder vent temps especially on a o-tube system but the compressor cycle times will be pretty short and this will eventually cause the clutch and/or coil to fail sooner.

Charging and filling oil is ideally done at the accumulator because the suction hose at the bottom of it has a metered orifice which will regulate the amount of oil allowed to enter the compressor. Because the refer is the vehicle for the oil, it (in a perfect scenario) will all collect at the accumulator like a reservoir and the orifice takes care of volume distribution. Adding oil anywhere else requires the refer to cycle it back to the accumulator and can be hard on the compressor and o tube if it's over capacity or collected in the high side trying to make it's way to the accumulator through the o tube along with a bunch of refer....

Man, you're almost spot on. Really good info, but the low side pressure of 75 in 75 degree weather is a tab high. This is the formula I use and it works well.

Ambient Temps

65=25-35 psi

70=35-40psi

80=40-50psi

90=45-55psi

95=50-55

100=50-55psi

110=50-55psi

Anything over 55psi on the low side is usually considered too high.

 

[iamtheshaner]

I said static pressures - engine off, cold (hasn't been run like a dog for an hour and shut off). Both high and low side are equal engine off and the static pressures should be *about* what your ambient temp is.

You can only trust your internet charts so much. Humidity is HUGE when it comes to the performance of a refrigeration system.

My best advice is to charge it to static temps, if your compressor opens the clutch a ~22psi low side and closes the clutch at ~45psi low side, your vent temps are 20* colder than ambient or better and your high side never exceeds 350psi in the dead of summer - it's operating better than 90% of the systems on the road.

 

[laddanator]

I said static pressures - engine off, cold (hasn't been run like a dog for an hour and shut off). Both high and low side are equal engine off and the static pressures should be *about* what your ambient temp is.

You can only trust your internet charts so much. Humidity is HUGE when it comes to the performance of a refrigeration system.

My best advice is to charge it to static temps, if your compressor opens the clutch a ~22psi low side and closes the clutch at ~45psi low side, your vent temps are 20* colder than ambient or better and your high side never exceeds 350psi in the dead of summer - it's operating better than 90% of the systems on the road.

Reread your comment and I missed the static part, sorry. I was going by that formula before internet was invented!

 

[SVT CAMR]

Well that AC pulley was a 100 dollar mistake. Motorcraft part number F5VY19D784A OR YB-521

BUT I found the problem it ended up being the Serpentine belt! Go figure. I would have never thought in a million years. 7 hours later and multiple screwing around. Oh well. Belt Motorcraft part number JK6982D or F8AZ-8260AA

I think my Cobra was pissed that I cut it's balls off and put it back to somewhat stock. So it had to make the final install chapter a bad one for me.

It makes sense because when I put the stock pulleys back on I noticed the belt had a lot more tension on it than it had with the UD pulleys. At the time i just noticed it but did not think anything of it. Something my Father told me and it bit me in the ass. "You make one change at a time on the car".

 

[SVT CAMR]

Thank You!

if the compressor is constantly cycling, especially when set on the max setting you are likely still under charged (if you hook up your manifold set again and watch - youll see low side pressure drop, the compressor will kick off, youll see the low side pressure come up again and then the compressor restarts. If it keeps doing this at the same pressures over and over you are under charged).

as mentioned, if you had 2.2 lbs in 3 little cans you likely did not get a full 2.2lbs of charge in the system (hell you can rub your hands together to get them warm and hold the can tight and you'll see that you're getting more freon out of the can still)

another thing to add about refrigerants with leak stop and such, supposedly when a compressor fails and that garbage is in there it makes a NASTY black residue thats extremely difficult, if not impossible, to completely remove)

Thanks for this valuable info. I will revisit the system when it warms up. It still cycles on and off in very short spurts with outside temps in the 60 here now. I was just afraid to over charge.

I will take all the advise you gave about the static pressure test. I will wait till it is 75-80 degrees out and with the AC off and see where my pressure reads.

The both of you have thrown out some great info in this thread. Honestly at first read I had no idea what you were talking about. The more you post and dummy it down the more it is making sense. I did get side tracked with tho squeal issue but i'm listening.

Thanks guys.:read:

 

[iamtheshaner]

I'm not trying to crap on anyone else's help here...and I will have to look over the wiring diagram for your car just to make sure I'm 100% correct instead of the 99.9% I'm at now...

But this talk about your low side pressures and cycle times is fuss about nothing. The low side pressure switch interrupts the compressor at about 22psi. I say "about" because there are always little variances in the switches and in gauge sets. It will leave the compressor off until the low side gets back to about 44psi. Usually, on a nice dry day between 70 and 90 degrees you can expect that compressor to cycle pretty quickly sometimes 10-15 seconds. It's completely normal for the compressor to cycle at the same pressures. Its a design characteristic of a low side switch and the reason they call it a Cycling Clutch Orifice Tube refrigeration system