Another AC thread

[cw212010]

Hi all,

So - I've replaced my compressor as the last one seized.

I've tried charging the AC to no avail. The system should be clean in that there wouldn't have been any debris present as the compressor didn't self destruct.

Everything is connected however I can't hear the compressor engaging when I hit the AC button in the car. I did have a leak which has since been sorted. Can anyone advise what else I should try?

The only port I know of is the one down by the drivers headlight - where else should I be looking?

 

[Joe in NY]

Did you pull at least an hour vacuum on the system?

There are two ports. High side and Low side.

 

[TechGuru]

Good grief, not another one, seems like we get 3-4 a week since it became summer.

First lets make sure your definition is correct.

With scroll compressors especially there is a difference between "locked up" and "seized up".

Seized Up: Black death (lack of oil causing over heating) will cause the compressor to slowly seize up and spread contaminants throughout the system which requires replacing everything but the hoses and evaporator.

Locked up: Occurs suddenly when there is a catastrophic failure of compressor internals usually due to age and not lack of oil. One can usually get away with just replacing the compressor in this situation but since there would be no warranty I would only use a salvage yard compressor.

They're usually noisy from loose internals before something comes apart and it locks up.

Think of locked up as a engine with a thrown piston rod.

Think of seized up as a engine with piston rings seized to the cylinder walls and rod bearings seized with the crank and rods (due to lack of oil).

Now since you only replaced your compressor I'm assuming yours locked up.

First I hope you replaced the two O rings on the manifold to compressor connection and put 4 oz of PAG46 oil in the compressor.

Second you should have vacuumed the system via the low port on the passenger side (on top of the accumulator) for at least an hour depending on the size of the vacuum pump.

Third you need to add 3 cans of DuPont Suva R134a refrigerant if you have front a/c only, if you have separately rear a/c let me know and I'll look up how much that needs.

I usually get 1 can in with the engine off then turn the engine on and the a/c on max cool and fan on 4 and put the rest of the cans in. The compressor should start cycling after 1-2 cans.

If compressor is not coming on check the connection to the clutch first since that is the only thing that should have been messed with since it quitting.

 

[cw212010]

Well I'm in bother then. The old one started making noises and one day just locked up and stalled the engine.

I've literally bolted on a new compressor and that's it. The new one had a vacuum on it when I popped off the disposable cover on the connection. I've not put any oil whatsoever in to the compressor. If I am to put oil in the compressor which of the two holes am I filling?

In all honesty I tried to fill the refrigerant via the low port on the passenger side, I've never tried to vacuum anything. The vehicle does have the system in the rear.

If I were to take this to a shop how much should I expect to pay to get them to resolve it since it appears I can't tie my shoelaces?

 

[TechGuru]

Ask them how much it would be to vacuum and charge a empty system with 56oz of refrigerant and 4oz or PAG46 oil. Assuming it's empty, if they have to recover what is in it they may charge more. So if you have not put more than 1 can in it I would dump it out.

Note for everyone: 34oz (2.8 cans, just use 3 considering fill hose loss) front a/c only , 56oz (4.6 cans) with the separately controlled rear a/c that has vents in the ceiling.

 

[Joe in NY]

I was quoted around $140 to $150 for a vac and refill.

But you have to add the oil still.

A/C systems are not as simple as everyone makes them out be.. The duration of the vacuum is far more important than how far down into a deep vacuum you get.

Also, 3 12oz cans will OVERCHARGE a front AC only system. I did that for mine. I know it's overcharged because it freezes all the way back to the compressor at 1,500 rpm as per the book. That is BAD. I have liquid flooding the compressor. I am correcting my mistake. Just FYI.

 

[Number Twelve]

New oil goes in the suction side of the compressor.

I've never tried to vacuum anything.

This is a definite indicator that you should work with the shoe laces. Working A/C from a position of, "clueless" will cause expensive problems (not implying that any A/C problems are cheap).
I'm happy enough that you could bolt on a compressor, but you need people with real gauges and equipment. There is a butt load of things you need to know to be good at it. Yeah, it looks simple when a pro does it, but it looks simple because he's a pro. He went through a checklist most people can't even imagine to arrive at: "this, then this, then that".

 

[imp]

New oil goes in the suction side of the compressor.

This is a definite indicator that you should work with the shoe laces. Working A/C from a position of, "clueless" will cause expensive problems (not implying that any A/C problems are cheap).
I'm happy enough that you could bolt on a compressor, but you need people with real gauges and equipment. There is a butt load of things you need to know to be good at it. Yeah, it looks simple when a pro does it, but it looks simple because he's a pro. He went through a checklist most people can't even imagine to arrive at: "this, then this, then that".

You're giving a novice a "bad break", don't-cha think? HELP is more than just ridicule, unless YOU are the SUPREME EXPERT. imp

 

[Number Twelve]

You're giving a novice a "bad break", don't-cha think? HELP is more than just ridicule, unless YOU are the SUPREME EXPERT. imp

You don't like a bit of happy conversation?
I'll just keep my 40 years of full time HVAC work and State License as a Certified HVAC designer to myself in the future.

 

[Donystoy]

New oil goes in the suction side of the compressor.

This is a definite indicator that you should work with the shoe laces. Working A/C from a position of, "clueless" will cause expensive problems (not implying that any A/C problems are cheap).
I'm happy enough that you could bolt on a compressor, but you need people with real gauges and equipment. There is a butt load of things you need to know to be good at it. Yeah, it looks simple when a pro does it, but it looks simple because he's a pro. He went through a checklist most people can't even imagine to arrive at: "this, then this, then that".

Number twelve is 100% correct. To properly repair any air conditioning system there is a procedure and system knowledge that should be followed for proper system operation. After the system is sealed it must be properly evacuated to a certain micron level and then have the vacuum only broken with the opening of the refrigerant tank valve. This will eliminate the entry of air or other contaminates into the system that will rapidly cause acid and corrosion within the system. Most new air conditioning compressors come with the proper level of oil already in them. Proper refrigerant charge is also critical as an under charge will starve the compressor of cooling and cause premature failure. Of course an over charge will cause obvious other problems; blowing hoses, comp failure etc.
I also worked in the industry for almost 40 years and have experienced burns from liquid refrigerant and was almost blinded once by some ones "lack of knowledge". .

 

[Rakun12]

I recently fixed the wire harness issue from the oil catch tray that rubs through the harness. I spliced in new pieces of wire for the solenoid wire and the two compressor wires. I was praying this was the fix for the compressor. Nope. My question is can I jump both the high and low pressure switches with a paper clip to try and get the compressor to come on? 2002 Mercury Mountaineer V8 AWD. I've checked all the AC fuses and they are good. Continuity checks also to verify them.

 

[Donystoy]

I recently fixed the wire harness issue from the oil catch tray that rubs through the harness. I spliced in new pieces of wire for the solenoid wire and the two compressor wires. I was praying this was the fix for the compressor. Nope. My question is can I jump both the high and low pressure switches with a paper clip to try and get the compressor to come on? 2002 Mercury Mountaineer V8 AWD. I've checked all the AC fuses and they are good. Continuity checks also to verify them.

Just a momentary shorting out of the low pressure switch is fine and will tell you if it is open because of the system been low on refrigerant gas. The high pressure switch should be closed unless it is defective. If shorting out of the switch does not turn on the compressor you might have an issue with relays, fuses etc.

 

[TechGuru]

The duration of the vacuum is far more important than how far down into a deep vacuum you get.

Also, 3 12oz cans will OVERCHARGE a front AC only system. I did that for mine. I know it's overcharged because it freezes all the way back to the compressor at 1,500 rpm as per the book. That is BAD. I have liquid flooding the compressor. I am correcting my mistake. Just FYI.

I've always been able to get my vac to peg out on my gauge so over 30.

12oz x 3 = 36oz and it requires 34oz. Yes I know on paper this should overcharge but in practice it does not unless maybe you are charging with some short Walmart/Autozone charging hose. When using my manifold with 5 foot hoses connected to both high and low and the small amounts left in the cans I easily loose the 2 extra ounces especially considering the high hose has liquid in it when I disconnect it.

You don't like a bit of happy conversation?
I'll just keep my 40 years of full time HVAC work and State License as a Certified HVAC designer to myself in the future.

I have both HVAC and MVAC EPA certs just so I can buy R22 and R12.

 

[Joe in NY]

That is if you leave the liquid in your gauge set and lines. I always dump everything into the low side and let the system bring it down to just 30 psi of gas for low and high side.

 

[TechGuru]

That is if you leave the liquid in your gauge set and lines. I always dump everything into the low side and let the system bring it down to just 30 psi of gas for low and high side.

I fill though the low of course but I monitor the high while I'm filling so that if I discover the orifice is clogged that I don't fill for nothing. I disconnect the low while it's running so the pressure on it is in the 30's when disconnecting, as for the high side if I'm in a rush I'll disconnect while it's running which at that pressure it's liquid in the hose, if I have the time I'll turn it off and let the high/low pressures equalize so I can disconnect the high at the equalized pressure.

I think I get what you're saying about also dumping the high into the low but I don't have valves at the ends of my hoses to be able to do that. Well, it depends on which ends I'm using, if I'm working on my older R12 cars then no (even though they've been upgraded to R134a I did not put conversion ports on them), but my R134a adapters have cut offs in them when disconnected.