going to install ac compressor

[tnporsche]

I was going to install a new compressor, as soon as it gets here, and I just wanted to do a run through with you guys.

I have a new dryer and compressor. I plan on using freeze 12 and using the vac pump from auto-zone.

I have filled this system b4 and it usually takes 2 1/2 12 oz cans of freon and small can of oil. Is that about right?

I usually pull the vac
Install can of oil
Install freon until there are no more bubbles in sight glass

I just wanted to check because I have read that overcharging can damage the compressor seals,

and I have never figured out how the gages tell me anything other than the difference from high side to low side when running, (tells me that it is pumping. )

Any tips appreciated

[aj951]

tnporsche,

I just did this back in July. When you say "new compressor" are you talking about a factory rebuilt compressor or new retrofit like Kuehl or Sandeen? I installed a new Kuehl compressor and it came loaded with the correct oil. Make sure you know how much oil comes in the new compressor if you are going to add oil with the charge or you will coat the condenser and evaporator with too much oil. I had to drain and measure the oil in my new compressor in order to know exactly how much oil it came with. I too used Freeze12 and I am satisfied with the results, although I don't think it performs as well as R12.

Here is a link to a Freeze12 conversion chart that will tell you the correct pressure readings. I used about 2 and 1/2, 12Oz cans which is approx 90% of the original 33Oz charge for the system. http://www.freeze12.com/techsup.htm. With Freeze12 you will still see some bubbles in the sight glass when the system is charged correctly, that is normal. If charging with R12there should not be any bubbles.

I also recommend removing the expansion valve and flushing the entire system (lines, condenser, evaporator) with a good AC flush, then install a new expansion valve.

By the way, it's like in the teens right now in the deep South. You really need that AC right now?

Good Luck!

[many944s]

You should really watch the pressure on both the high side, and low side when charging the system. The only real way to optimize the A/C charge is by calculating the pressure differential in relation to the temperature of the compressed freon/refrigerant. See if there is someplace near you that you can borrow a guage tree when you charge the system.

If you can't find a tree, I have a spare set. Drop me a line and I can loan it to you. If you were closer I'd have you stop by the shop and I'd hook it up to the charging machine We worked wonders on Speedy's system when he was here for the belt gathering.

Let me know.
-Nick

[dfwdiesel]

Last time I checked R12 was not too expensive at around $25 a pound last time I checked. Really expensive though if you pay a reasonable shop mark up. There are online tests you can get a mobile license to buy it.


Run a really long vacuum. Set of R12 gauges are not expensive new on EBAY.

The pressures will be ambient temp specific. Wieghing it in can help get to close also.

I work on residential and light commerical HVAC for a living. I only work on mobile air when I really have to.

Of course replace the drier. R12 is really easy to work with and can hold up very well.
john

[tnporsche]

Originally Posted by aj951

By the way, it's like in the teens right now in the deep South. You really need that AC right now?

Good Luck!

The windows fog really bad without ac on ours. Yes it is a little warmer today however it might make it over freeze mark.

I have never tried to put freon in when it was this cold. Is that going to cause a problem?

Those press readings (table from link )
is that the low side press when full?

I have 134a gauges with adapters

As far as comp goes its remanufactured NipponDenso 10P15E

[aj951]

I haven't tried it in cold temps either so I can't add anything there.

I think the pressure table is for the high side, that is how I used it. Look at the tech tips on the website as well, they are helpful.

[dfwdiesel]

Pressures will be much lower when it it cold. If you put too much freon in things can get ugly such as liquid in the compressor pistons or starting a leak.

I like to charge systems when it is warm such as 70 degree to 100. But get paid to charge home and light commerical systems down to 40 degrees.

Don't think about charging the car unless you have an ambient air temp/pressure chart. You want to hit the target just right. Too little freon
poor cooling/freeze up, too much less coolingalso and asking for big repair issues.
John

[tnporsche]

Just to update thread,(in reference to post #2)

the temp chart instructions on this link are cool. (pardon the pun LOL)

http://www.freeze12.com/Tech%20Tips/techtip7.pdf

[WaA420]

The temperatures and pressures on the T/P chart are for static readings of refridgerant and also used to determine superheat and subcool.

When I recharge a system I fix any leaks and then pull into a deep vacuum and use the vacuum to pull in the refridgerant. And I put in how many ounces the system says to hold.

[Razorback1980]

Originally Posted by WaA420

And I put in how many ounces the system says to hold.

I do that as well, but I think in this case he is using a different refrigerant and the amounts will not be the same.