AC expert help
Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
AC expert help
I got a 1994 Aerostar and I replaced the Compressor with a known factory good one. the old one just locked up, so I pulled over and unplugged it. I dumped the old oil out. poured 3.5 oz of pag 100 oil in. changed the Orifice tube front, no trash was in the old one. This has rear ac and it does not have a orifice rear, just a valve.
Before I change out the Dryer, I wanted to check for leaks. "Found High Pressure valve" was leaking" replaced the whole unit. so I got a can of freon. jumped the pressure valve and it is having a hard time taking the freon. it took about half a can then just takes forever after that. It will cycle for 5 seconds, pause for 3 seconds and then 5 again. never tries to get cold.
I have the Factory Service manual. and it says it has a leak when the compressor cycles like that. but it's holding steady so far. Should I install the new dryer and then pull a vacuum. then see if it leaks.
Before I change out the Dryer, I wanted to check for leaks. "Found High Pressure valve" was leaking" replaced the whole unit. so I got a can of freon. jumped the pressure valve and it is having a hard time taking the freon. it took about half a can then just takes forever after that. It will cycle for 5 seconds, pause for 3 seconds and then 5 again. never tries to get cold.
I have the Factory Service manual. and it says it has a leak when the compressor cycles like that. but it's holding steady so far. Should I install the new dryer and then pull a vacuum. then see if it leaks.
Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
Well after turning the orifice tube in the right direction! it started to take a can. So I stopped and will see if the pressure holds over night. If it does, I will change out the Dryer and clean and straighten any fins that are bent over. then pull a vacuum for 45 minutes check for any small leaks and recharge.
I don't know how it worked to start with. If the orifice is in backwards, it should have never got cold.
I don't know how it worked to start with. If the orifice is in backwards, it should have never got cold.
Last edited by Muffinman; Jun 2, 2010 at 08:17 PM. Reason: Orifice
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
You don't mention pulling a vacuum on the system before charging it. Did you? If not, the AC will never cool well due to the air in the system. Removing the air is essential.
Do you know what the High Side pressure is? It's very possible that debris from the old compressor has clogged the condenser and id causing the High Side to skyrocket. There's nowhere for the refrigerant to go, so it won't pull any more in. Was there any metallic debris or gray "goo" on the orifice tube? If so, that's compressor innards and you'll probably need a condenser.
Do you know what the High Side pressure is? It's very possible that debris from the old compressor has clogged the condenser and id causing the High Side to skyrocket. There's nowhere for the refrigerant to go, so it won't pull any more in. Was there any metallic debris or gray "goo" on the orifice tube? If so, that's compressor innards and you'll probably need a condenser.
Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
Like I said, I pulled a vacuum to to find any leaks. After replacing the compressor. No there was metal or black death in the old orifice or compressor.
The problem was the the old orifice tube had been put on backwards. When I removed it, I put the new in the same way, the old one come out. After looking at the old one I realized the flow arrow was pointing in the wrong direction. Problem solved.
My main worry was using pag 100, it's a sponge for moister. So it has to be dry as I can get it from the start.
The problem was the the old orifice tube had been put on backwards. When I removed it, I put the new in the same way, the old one come out. After looking at the old one I realized the flow arrow was pointing in the wrong direction. Problem solved.
My main worry was using pag 100, it's a sponge for moister. So it has to be dry as I can get it from the start.
Lead Driver
Joined: Sep 2003
Posts: 7,010
Likes: 203
From: SoCal
The orifice tube is just a restriction, so it can work if installed backwards. It may pose a greater restriction than designed for, so maybe that's why you saw the freon fill so slowly. When you took it out, did you check to make sure nothing was clogging it? That doesn't matter now, since it there was. it probably got blown into the evaporator.
It's hard to clog the stock condenser, since it uses parallel tubes.
When I did my system last year, I pulled apart both the front and rear systems to clean them out. I did not find much in the rear system.
One other thing about pulling a vacuum: the Schrader valves are spring loaded, and designed to seal harder with internal pressure. Since you're drawing a vacuum to pull out moisture, the atmospheric pressure will push against the valve springs, and make the valve seal loose. In my case, I actually found one of them leaking under vacuum conditions. So I installed the caps over the valves as often as I can, especially just before doing a leak-up test.
It's hard to clog the stock condenser, since it uses parallel tubes.
When I did my system last year, I pulled apart both the front and rear systems to clean them out. I did not find much in the rear system.
One other thing about pulling a vacuum: the Schrader valves are spring loaded, and designed to seal harder with internal pressure. Since you're drawing a vacuum to pull out moisture, the atmospheric pressure will push against the valve springs, and make the valve seal loose. In my case, I actually found one of them leaking under vacuum conditions. So I installed the caps over the valves as often as I can, especially just before doing a leak-up test.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
]Like I said, I pulled a vacuum to to find any leaks. After replacing the compressor. No there was metal or black death in the old orifice or compressor.
No. You said you wanted to check for leaks and then replacing the valve. No mention of a vacuum.
The problem was the the old orifice tube had been put on backwards. When I removed it, I put the new in the same way, the old one come out. After looking at the old one I realized the flow arrow was pointing in the wrong direction. Problem solved.
That is a problem, but I've seen systems work with the tube in backward. Like XLT said, it may be a bit more restriction, but it's possible that the system seemed to work fine.
My main worry was using pag 100, it's a sponge for moister. So it has to be dry as I can get it from the start.
All US built Ford systems normally use PAG-46, but PAG-100 won't hurt anything. All PAG oil is hygroscopic and soak up moisture like a sponge. This is why you should actually replace the accumulator before adding oil from a sealed container and pull a hard vacuum on the system.
XLT, plugged condensers are very common after a compressor failure. Each of those parallel tubes in divided internally into 4-5 small, separate passages. It takes very little debris to obstruct the flow enough that the high side pressure skyrockets
No. You said you wanted to check for leaks and then replacing the valve. No mention of a vacuum.
The problem was the the old orifice tube had been put on backwards. When I removed it, I put the new in the same way, the old one come out. After looking at the old one I realized the flow arrow was pointing in the wrong direction. Problem solved.
That is a problem, but I've seen systems work with the tube in backward. Like XLT said, it may be a bit more restriction, but it's possible that the system seemed to work fine.
My main worry was using pag 100, it's a sponge for moister. So it has to be dry as I can get it from the start.
All US built Ford systems normally use PAG-46, but PAG-100 won't hurt anything. All PAG oil is hygroscopic and soak up moisture like a sponge. This is why you should actually replace the accumulator before adding oil from a sealed container and pull a hard vacuum on the system.
XLT, plugged condensers are very common after a compressor failure. Each of those parallel tubes in divided internally into 4-5 small, separate passages. It takes very little debris to obstruct the flow enough that the high side pressure skyrockets
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Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
The orifice tube is just a restriction, so it can work if installed backwards. It may pose a greater restriction than designed for, so maybe that's why you saw the freon fill so slowly. When you took it out, did you check to make sure nothing was clogging it? That doesn't matter now, since it there was. it probably got blown into the evaporator.
It's hard to clog the stock condenser, since it uses parallel tubes.
When I did my system last year, I pulled apart both the front and rear systems to clean them out. I did not find much in the rear system.
One other thing about pulling a vacuum: the Schrader valves are spring loaded, and designed to seal harder with internal pressure. Since you're drawing a vacuum to pull out moisture, the atmospheric pressure will push against the valve springs, and make the valve seal loose. In my case, I actually found one of them leaking under vacuum conditions. So I installed the caps over the valves as often as I can, especially just before doing a leak-up test.
It's hard to clog the stock condenser, since it uses parallel tubes.
When I did my system last year, I pulled apart both the front and rear systems to clean them out. I did not find much in the rear system.
One other thing about pulling a vacuum: the Schrader valves are spring loaded, and designed to seal harder with internal pressure. Since you're drawing a vacuum to pull out moisture, the atmospheric pressure will push against the valve springs, and make the valve seal loose. In my case, I actually found one of them leaking under vacuum conditions. So I installed the caps over the valves as often as I can, especially just before doing a leak-up test.
I looked at the Evaporator when I had to change the orifice, nothing I could see. I used compressed air to blow that out. Wish I had some nitrogen then.
The rear just has a expansion valve. It was ok back there. nice and clean now.
I never thought of the high side valve leaking when pulling a Vacuum. it was only a $3.00 part so no big cost.
Anyway I checked the pressure this morning, still the same. So I installed the accumulator and drained the compressor oil and changed it again. fixing to go pull a vacuum for 45 minutes and recharge.
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Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
Well I got it fixed and blowing cold again. I think the fan clutch needs to be replaced cause at idle, its not as cold. It turned easy with the hand with little resistance. so I will replace that before the temps here start hitting triple digits.
Lead Driver
Joined: Sep 2003
Posts: 7,010
Likes: 203
From: SoCal
Are you sure the clutch is slipping? Usually it won't be as cold at idle as when you're moving at any decent speed. What air temps are you seeing at idle or cruising? (Please be careful checking the temps while cruising.)
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
Weak AC at idle is the first sign of a clutch getting weak. It will effect the AC long before you see a rise in engine temp.
Thread Starter
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Laughing Gas
Joined: Jun 2004
Posts: 1,240
Likes: 3
From: Dallas, Texas
Thats what I thought. I looked it up in the service manual, to see how to trouble shot it. It says the same thing about Normal High-Normal Low but compressor runs all the time. replace AC Fan or clutch or both. I would like to put a electric fan in. but have no idea what the best unit to use is. I heard finding new fan blades for Aerostars is hard to get.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
Thats what I thought. I looked it up in the service manual, to see how to trouble shot it. It says the same thing about Normal High-Normal Low but compressor runs all the time. replace AC Fan or clutch or both. I would like to put a electric fan in. but have no idea what the best unit to use is. I heard finding new fan blades for Aerostars is hard to get.
As for electric fans, there are many different sizes available aftermarket.
On the used side of things, Windstar fans are very popular because they move a lot of air. Lincoln Mark VIII fans are very sought after because they will nearly pull the vehicle down the road.
If you have room, a Crown Vic/Towncar/Gr.Marquis fan-shroud combo is a great replacement for the mechanical fan on a FWD vehicle. The electric fan is mounted in the shroud.
Postmaster
Joined: Oct 2009
Posts: 3,432
Likes: 7
That is normal. You don't get as much airflow at idle. There is a plastic strip on the underside of the radiator that bridges the gap between the radiator and the condenser. If it is missing or not seated properly, you can get air that flows through the radiator, keeping the engine cool, but that bypasses the condenser. I do agree though, your clutch may be toast.