AC Leaks

[negusm]

I plan on getting the dash apart and fixing the heater core during thanksgiving.

There is an AC "core" (what is it called?) in the heater box too. Should I replace that too?

I checked my lines and there is no pressure left in them. The refrigerant must have leaked out again so now I need to find the leak. I'd hate to find it all the way in the heater and have to drop the dash AGAIN. Is there any way of testing it? How much are replacements? Do they go bad often?

Any help appreciated. Thanks.

-Mike

[85 Notchback]

It's a 20 year old car, I would under no circumstances expect the free-on to still be in there. I'm not quite sure where to get a refill, my uncles a plumber I just get them from him for my brothers camaro, and my truck.

[negusm]

It's a 20 year old car, I would under no circumstances expect the free-on to still be in there. I'm not quite sure where to get a refill, my uncles a plumber I just get them from him for my brothers camaro, and my truck.

It was charged this past spring after the body guy got it all finished up. At that time it was converted over to the new refrigerant.

It leaked out in a span of like 6-9 months. So there is a leak somewhere in the system that I need to fix.

-Mike

[slickshift]

If he charged it up w/ the new stuff w/o converting over your whole system, (I mean hardware wise, compressor, lines, etc.) it would leak out after 6-9 months on a 20 year old car no problem
I would expect it to by then actually
The new stuff is "smaller" on a molecular level, and older, well any, R-12 spec sytem won't hold it for long
Did he convert your system, or just load up the old one w/new juice?

[negusm]

If he charged it up w/ the new stuff w/o converting over your whole system, (I mean hardware wise, compressor, lines, etc.) it would leak out after 6-9 months on a 20 year old car no problem
I would expect it to by then actually
The new stuff is "smaller" on a molecular level, and older, well any, R-12 spec sytem won't hold it for long
Did he convert your system, or just load up the old one w/new juice?

I have to ask...I know the evaporator canister was changed.

I think the AC compressor was not changed or rebuilt. I have a new one of those. Do I need new lines or can I get new fittings or bushings or o-rings or what?

I guess what I really need to know for the short term is how to tell if the AC "core" in the heater is any good. I just do NOT want to have to drop my dash again after I get in there. I don't mind replacing stuff in the engine bay.

How much are they to replace?

-Mike

[foxmustangrestoration]

OK Mike. I am an ASE certified A/C tech. You do not have to replace your compressor to do a proper A/C retrofit. You do have to drain all of the mineral oil out of the system. To drain the compressor you need to take it off, hold it up side down and turn the clutch over about 20-30 times. Make sure you turn over the clutch and not just the pulley. Then to get the rest out you need to flush it out with a good A/C fluch solvent.. DO NOT PUT THE A/C FLUSH IN THE COMPRESSOR. IT WILL RUIN IT. Take all the lines off and flush the condensor(the radiator type thing in front of the radiator) the evaporator( that is what is inside your dash. It is called an A/C evaporator) and all the lines. What you called the evaporator canister is actually called the accumulator. REPLACE THAT ANYTIME YOU ONPEN THE A/C SYSTEM. The reason for that is because the function of the accumulator is to absorb all moisture out of the A/C system. There is chemical balls inside of it called decicant. That chemical absorbs moisture. But it can only hold so much. So when you open the system humidity is absorb by the decicant making the accumulator no good. when moisture mixes with the A/C oil it can turn the A/C oil to an acid that can eat your A/C system from the inside out. That is the same reason you must put the system under 31 inches of vacumm for at least 20m minutes. That boils the moisture out of the system.
Now when you put the A/C oil back in use ester oil. You must spread 8 ounces of it through out the system. DO NOT USE MINERAL OIL OR PAG OIL. Mineral oil is for r-12 freon only and PAG oil is for R-134a system that never had r-12 in it. after filling it with freon MAKE SURE TO TURN THE CLUTCH (NOT JUST THE PULLEY) OVER BY HAND AT LEAST 10 TIMES. That moves the new oil you just put in into the lines. You do this because it can blow the copressor up. It can not compress a liquid just like any motor with pistons and cylinders.
OK the only way to tell for sure if a evaporator or any A/C is leaking is to put dye in the system and run it. When it leaks out it can be seen by the naked eye but is best seen in a black light. It glows yellow in a black light. other ways is to look for wet areas that has collected dust and other crap from the air. It is wet because when freon leaks out so does the oil. And oil does not wash away. So it sticks to the part near the leak. Then you always have freon detectors but they are about $400 and you need the system to be full with those.
On mustang you need to cut the top off of the heater-A/c box to get the evaporator out. It is the only way to do it unfortunatly. There is an outline on the box above the evaporator were you need to cut.
You do not need to replace the system when retrofitting even though the new freon is smaller than the old. I have an 85 with the original A/C system in it. I retrofitted it without replacing any parts and it is still blowing cold. I did it 3 years ago. The most common place for fords to leak freon is the O-rings at the hoses. Replace all of those when you do your A/C job.
New after market evaporators run about $100. New after market heater cores are about $15-$30. If there is alot of leaves and debri in the A/C evaporator area I would replace it no matter what.
Like I said, I am a certified tech and I am in Florida so I do ALOT of A/C jobs. If you need help even diagnosing the A/C useing the gauges I can help. I dont know if this is against the rules but I am going to post my Phone # if you need help with the A/C and you or anyone would like to call. 772-834-8905. Thanks Matt

[negusm]

Thanks man.

I will print this out. It hope the evaporator is good. I'd hate to have to cut the heater box.

Can I put some air pressure into the evaporator and see if it is leaking?

If it is ok, how much pressure? What's the best way to do it? Is there a home "dye" test kit?

Since I now can disconnect both the coolant and AC line, does anybody know if you can drop the heater out of a car without pulling the dash?

-Mike

[foxmustangrestoration]

You HAVE to pull the dash to do the heater core. I know, it sucks. As far as putting air into the system that really doesnt work because evap leaks are usually so small that it will take weeks to months to leak out. So you would not beable to hear it. Some poeple to make homemade adaptors to fill the entire A/C system with air and use soapy water to spray on the system. Then a leak will bubble up. But you cant see the evap till you take it apart. Air pressure is full shop pressure(120 to 145 psi)
Most auto supply storers sell dye kits with glasses U- V lights and dye. I think they are about $50 and up.

[foxmustangrestoration]

By the way, do not get any of the dye on your cars paint. Worse than brake fluid. If you do you are in for another paint job. And when you put the new O-rings on, do not use A/C oil like the book tells you 2. Use di-electric grease. A/c oil will dry up in the heat of the motor and it will let the O-rings start to leak. Di-electric grease will not dry up and it does not hurt the o-rings.

[negusm]

Thanks. I may then just get another evaporator....just to be safe.

So like what are the odds that it is bad? Do they often go bad? I'm almost tempted to chance using the old one and trying to just redo all the hoses and o-rings.

-Mike

[foxmustangrestoration]

not dye I meant dont get any A/C/ flush on your paint. oops