Do my own AC?

[davepl]

I see that I can buy a reportedly decent set of manifold gauges for $56. Would that, some refrigerant, and a Hayes book make it something I can do myself, or should it be left to the professionals?

All the parts are new except the thing in the firewall (evaporator?). Compressor had oil in it, and I'm not sure if its compatible with 134 (it's a new unit from LMC, and I can't imagine they're selling R12 stuff). I have the LMC o-ring and lube kit. There are still going to be vestiges of whatever was in it before in the lines.

Based on the size of the fitting, a friend told me that it must have already been converted to 134 in the past, but I don't know how I'd verify that.

- Dave

Other lesson of the day: Oil will blast out of a new compressor when you take the plugs out of the back. Wear glasses!

[elimontfort]

You will need to pull a vacuum on the system also

[Andy4639]

I installed a complete orignal system in my 71 years ago. I have since converted it over to 134-A. So yes you can do it yourself.

[FirstOwner69]

Best left to the pros. I took them my 30# of R12 and let them handle it.

I'm a bit surprised you asked after your "bad day in the shop" thread I just read.

Jim

[Joe Pass]

Once all the components are in place you need to pull a vacuum in the system to remove any moister and also detect leaks that still may exist. Gages and vacuum pumps are more affordable now days but with out at least some training you will probably wont be successful at getting the system serviced. There are many U tube videos on this subject that may give you an insight on the procedure. My training has been in aviation a/c systems which don't really differ to much to automotive and I have installed a/c in many hotrods. I would take it to a reputable a/c shop and get the system serviced at least the first time and then you can later top it off with over the counter 134a cans if need be. The gages can tell you how the system is working with the differential pressure readings between the high and low sides and they can assist you in filling the system when you use a commercial size containers (30lbs).

[71swb4x4]

Originally Posted by FirstOwner69

I'm a bit surprised you asked after your "bad day in the shop" thread I just read.

Jim, you should be encouraging him to do it so we have another entertaining thread to read!

I am laughing WITH you Dave.

[davepl]

After yesterday I thought I'd be safer if I stuck to inert gas for a while :-)

Looks like a 30# tank is $130 on Amazon so you wouldn't want to waste it in a mistake. I already ordered a vacuum pump because I've left the dryer open since I installed it. Maybe it only needs an hour under vacuum but I want to make sure it's dry.

That should also tell me if I have leaks, right?

Andy (or anyone), what should I do about the oil that shipped in the compressor?

[FirstOwner69]

Originally Posted by 71swb4x4

Jim, you should be encouraging him to do it so we have another entertaining thread to read!

I am laughing WITH you Dave.

Oh... sure... I forgot about that! Go for it Dave!!!

Seriously, I did almost everything other than the A/C myself. As ststed above, that's best left to the pros.

[FirstOwner69]

Originally Posted by davepl

Andy (or anyone), what should I do about the oil that shipped in the compressor?

Not sure about all compressors, but mine stated R12 on the label.

[piecesparts]

If it is R-12, do you have a certificate to purchase it? If it is R-134A, then you can buy it at Sam's club. If not, then you need to just go to a pro and have them do it. There are a lot of things that if you have little experience in HVAC, that you need to consider as you charge your system up. Pulling a vacuum is definitely on of them--vacuum pumps are expensive, knowing when the charge is proper is another thing to watch for. R-12 is a little forgiving on the charge, but R-134A is restrictive on the exact amount of Freon, that you put in. Otherwise your evaporator coil will freeze over and then you lose your cool air flow to the cabin.

[Acorn]

If you already heave gauges and a vacuume pump its a good time to learn how to use them. Not having the tools is usually what keeps most weekend mechanics from doing this themself. In theory if you are using all new parts, you should not have any troubleshooting issues. Just make sure you use proper amount/type of oil, lube all o-rings when installing, pull a good vacuume, (something like 30 min-1hr per pound or something like that) and watch the gauges and see if they hold. If no leaks, charge the system. If it dosent work out for you THEN you take it to a "pro" The worst that will happen is you will be out a few puonds of freon.
I run electric fans on all my projects but if your not, I find it useful to put a shop fan in front of your condenser/radiator to simulate driving down the road and keep it from heating up and keeping your high side pressure down.
Never pass on an opportunity to learn! It's also an awesome feeling to be able to say that you built everything yourself!

[Andy4639]

If you have concerns on the oil once you have it in place take and have it cleaned out good by a shop. Are take it now and have the compressor swapped out are have them purge it out. I bought my stuff for the 134-A and all I did was vacuum it good.

[joey8383]

LMC sells R12 and R134a compressors. 134a uses PAG oil and R12 uses a mineral oil. If it is a r12 compressor, just dump oil out in to a measuring cup and leave compressor upside down over night to drain completely. Refill with PAG oil and vaccum and charge.
Using a vacuum pump to check for leaks is not a good idea. Best to use nitrogen and pressure it up to 150psig and soap bubble connections. Some people just use 134a to pressure test but that's up to them.... If you do decide to pressure test with refrigerant just remember the pressure will fluctuate as the outside temp changes. So you can't just set it at 150psig and let it stand overnight as a pressure test. Good luck.

[mrein3]

Originally Posted by davepl

After yesterday I thought I'd be safer if I stuck to inert gas for a while :-)

Looks like a 30# tank is $130 on Amazon so you wouldn't want to waste it in a mistake. I already ordered a vacuum pump because I've left the dryer open since I installed it. Maybe it only needs an hour under vacuum but I want to make sure it's dry.

That should also tell me if I have leaks, right?

Andy (or anyone), what should I do about the oil that shipped in the compressor?

To start with I would say DEFINITELY do your own AC. There really isn't anything to it. The service manual has a good write up and so far the only thing I think I've seen where you might have rework is the receiver/dryer. You really don't want to leave them open to the elements too long because they will do their job and pull moisture which, depending on your weather, might be bad if you live in a humid area. For the price of that component I'd buy a new one, leave it sealed until you're ready to go, then install it.

Regarding the compressor, flush it with the oil you are going to use for the system. I purchased a half a gallon of stuff compatible with R134a from ackits.com. It is the color of a chartreuse spinner bait - which they claim then helps with leak detection. That half a gallon I bought was enough to flush my compressor and fill the system. To flush it, add a measured amount, work the compressor by hand a few times around, then dump it out. Measure what comes out so you don't end up with too much oil in the system. I did that three times with my 40 year old compressor and never had a problem.

The vacuum pump I use I got at Harbor Fright. If you have a store local, print out one of those 20% off coupons and you'll get change back from a $100. If I was doing this daily in a shop that is the WRONG pump but for a back yard mechanic who is only going to use it once in a while it will work fine.

When you are ready to charge, you need to pull a vacuum first. If you can remember you high school chemistry teacher, pressure and temperature are related. If you pull a vacuum, you lower the boiling point of water. In that vacuum the moisture in the system boils and is expelled into the atmosphere. You want to get a vacuum of -30" Hg, close the valve on your gauge set, then leave it for 30 minutes. If 30 minutes later you still see -30" Hg on your gauge, you have no water in the system and no leaks. You are ready to charge it.

I wouldn't buy a 30 pound can of R134a. I saw an ad last sunday for R134a for $6.95/can. Buy 4 cans and call it good.

Now comes the tricky part. How much R134a to add? You want to start at 80% of what GM specified for R12. Then use your manifold gauge set to dial it in from there.

Once again I must stress, automotive AC isn't that complicated. There is nothing to be afraid of.

[brown7373]

As a friend of mine, more experienced than me said, A/C is "stupid simple". I got tired of dropping hundreds every time the A/C needed attention on several old cars. I bought the gauges, the Haynes book, a 30 lb tank and a vacuum pump. After reading and rereading the Haynes book, I do all my own A/C work. I sent my POA valves out to be recalibrated for 134a and I have better A/C in south Florida than I used to taking it to a professional...who either hadn't ever worked on this vintage A/C, or it had been so long he forgot. You can do it.

[joey8383]

A perfect 30"Hg vacuum is equivalent of positive pressure testing at 8 psig. This is why I say to use nitrogen or refrigerant and pressure it up to 150psi. It's ok to use a vacuum to leak check if you're using a micron gauge and make sure it hold a vacuum of 500 microns.

[hdff]

"All the parts are new except the thing in the firewall (evaporator?). " this statement tells me you need to take it to the shop!

[Andy4639]

If you buy the right parts which you already know you need R134-A stuff then do it yourself first. If you can't figure it out then and only then take it and have a shop finish it for you. Putting the system together is like any other parts you install. Try it what is going to hurt but your pride a little if you can't get it.