High and Low side a/c

SixgunSal said
Those are some good looking 90's. I got the fittings on - the high side would not take a shrader so I left it in the old fitting, and will find out when I put some gas in it if the red hose will still read. The blue one was pretty easy, I dremmeled down my smallest needle nose to make a tool. I keep wondering if I need to buy a cheapish manifold hose set for this. The manifold gage hoses I borrowed from Reilly's Auto has the rubber hose pieces that fit at the bottom inside all the hose hookups are broke and I've been running this vacuum pump for 2 hours and it won't get better then -15 - halfway to the 30 mark. I shut it off once and it didn't go back any so hopefully no leaks in the a/c. The searches I have done for only getting to -15 say its either the pump or the hose connections so thats why I wonder about the cheapish purchase of a manifold hose set. Is -15 good enough?

HI,

From reading your posts I can see you're fairly new to automotive A/C work and very likely these old Mopar systems. So, here are a few things to consider. If you have no idea what is in the present system it would be a good idea to take it to an A/C shop or borrow a refrigerant identifier and see what is in the system. While it looks like the old R-12 fittings are still in place and not R-134A adapters that's no assurance of what some one may have put in there. There are many internet sites that will give you some basic ideas on automotive A/C systems and how they operate and reading the shop manual is a good place to start. If you do convert to R-134A stay away from those cheap/quick conversion kits out there. A/C professionals refer to them as "Death Kits" as they can quickly lead to system and compressor damage.

To convert to R-134A you will need to use the proper oil in the compressor, flush out the oil R-12 mineral type oil and refill with an R-134A compatible oil. I like to use an ester based oil with is compatible with both R-12 and R-134A. You will also need to change the receiver /drier to and R-134A compatible type. All new receiver/driers today are both R-12 and R-134 A compatible. If you don't do this the R-134A will bust the old desiccant bag in the drier and spread desiccant through out the system and you'll have a real mess. 15 inches of vacuum is no where low enough and some thing is not right some where. A good tight system will easily get down to 28 inches and hold that vacuum for many hours. You are not anywhere near being able to recharge your system and get good results when done. Good A/C work requires attention to detail, it's not hard to do but short cuts will only get you in expensive trouble.