A/C question

[f.monroe]

I converted the A/C system to 134a and I have a couple of questions. How many ounces are required for a complete charge on a 1977 Chevy truck ? What temperature are you guys getting at the center vent on Max ? I replaced the compressor, hoses , drier, orifice tube, and evaporator core . The only thing not replaced was the condensor and high side line . It gets to about 42 deg at night while driving . During the day it is just getting in the 60's at the center vent . I think it may be overcharged . Also , where can I get the black putty material that was packed around the lower inlet of the evap core . Mine was dry and unusable . The auto parts store said they didnt have anything like it and my case is open right now at that spot . I am sure I am losing a little air through the 2 inch hole and I need to seal it . Thanks in advance . Frank

[Slonaker]

I have done the conversion on my truck. I can't really answer your questions for most part, but I will offer what I can (mainly a bump to your post ).

I have not measured my vent temperatures, but I can say that it cools well enough to be comfortable when the temps are in the high 90s. I doubt it would do that if your vent temps are in the 60s right now.

The previous owner replaced the evaporater core in mine, and left the sealer off everything. Like you, I think I am losing at lot of cool air because of it. I can smell hot engine smells with the A/C on, so that can't be good. If you find a source for the sealer, I would like to know what it is. Someone told me there is a product available in hardware stores that works, but i can't remember the details now.

You might ask around here:

http://acsource.net/acforum/

I used to read it regularly in its old format. I have not checked it out lately, but it is probably still a good resource.

Slonaker

[f.monroe]

Anyone else ? Frank

[bejay]

usually 75 to 85 percent of the rated r12 capacity there is usually a sticker under the hood that will give you the original freon capacity.
if you dont have access to a vacum pump and set of manifold guages you should probably have a shop pull a vacum on the system and fill it for you.
check another parts store for the insulating tape should come in a roll, if you cant find any try a local hardware store insulating pipe tape would probably work ok.
r134a does not usually perform as well as r12 most noticable on hot days at a stop or slower speed driving an additional electric cooling fan that runs when the a/c is on can help, along with a variable metering orfice tube that replaces the original style orfice tube can make the performance of r134a alot better.

[KShortell]

Originally Posted by f.monroe

Also , where can I get the black putty material that was packed around the lower inlet of the evap core . Mine was dry and unusable . The auto parts store said they didnt have anything like it and my case is open right now at that spot . I am sure I am losing a little air through the 2 inch hole and I need to seal it . Thanks in advance . Frank

Frank-

You're looking for 3M's Automotive Strip Caulk. I bought some from Year One. Before that, my Dad always had some lying around over the years. It's great stuff and highly useful!

http://products3.3m.com/catalog/us/e...eme_us_aad_3_0


It's $15 at Year One on their online catalog right now- Part # 3M8578.

Good luck!
Kevin

[gchemist]

The first conversion to R134 dropped the temps to into the 40s!! It would get so cold even at the lowest setting, I had to turn if off sometimes for a few minutes. The A/C would cool the cab in less than 30 seconds!! The guy that did the work was awsome!! Lately, I've had a bad streak of compressors. Same for A/C mechanics. I just can't get in touch with the first time mechanic. I need to replace the compressor again. This time I'm going to do the work myself. I bought an vacuum to pump down the system. I can replace all the parts myself. I can blow out the lines with IPA since I have a nice compressor at home. My brother has the gauges to recharge the system. I can't remember the correct amount of R134 to use. I'll see if I can find out in the next day or so.