Air Conditioning - Help needed with air conditioning compressor

This is a 20 year old Carrier 3-ton central air conditioning unit. I had trouble starting the compressor about one month ago. However, it did start after I shook the old run capacitor.

To improve the cooling efficiency I successfully changed the refrigerant to the new 22A envirosafe. After changing the unit worked fine for about a week (little improvement in cooling efficiency was seen in this time). I don't suspect a leak in the tubing.

After a week of using the unit, the compressor only hums; it does not start. The fan works fine and I dont think the problem lies within the thermostat because it seems to trigger the fan correctly.

I don't suspect the compressor to be faulty because it did compress the gas on the narrow (high pressure) side tubing when I did use it for that week.

The air conditioning unit trips the outside fuse after a few seconds of being on.

The compressor is not grounded and the three wires leading to it have little resistance.

I changed the run dual 440V AC 40/5 MFD capacitor and I still have the same results.

I did some research that a hard start kick is needed.

How can I add on or replace the capacitor in the series or parallel to fix the problem?
I cant seem to find the problem or a solution.
Much help is appreciated.


THANKS

I don't know what 22A is but keep in mind that the compressor determines the efficiency of the unit. If you put in a different refrigerant, you may change the compressors characteristics and overheat or overwork it. Maybe not too but I wanted you to think about that. Supco makes a few kinds of hard start kits. I like the one with the potential relay inside instead of the thermal timed one. http://www.supco.com/eclass.htm

Let the compressor cool off before you try restarting it. And make sure it isn't overcharged or lugging. Do an amp draw on it to be sure the new refrigerant isn't causing trouble.

I hope when you did the changeover you recovered the refrigerant as required and evacuated the system properly before introducing the new blend.

Ken

Im with Ken here what is 22a???? Some old units like that had a R502 in them I know. That would be like if you try and put in the new R410a you have to put in all new oil also. Also to charge the unit with 410a you have to put it in in liquid form not in as a gas .

ED :confused:

I may be wrong but I think 22A has propane in it. How do you know the compressor isn't shorted? What's the amp draw on start up? When the tech recharged it did he go by subcooling or superheat?

I wouldn't put one dime into a 20 year old unit. Your throwing your money out the window.

i am late getting in on this, but..

you shook the cap to get it going?!? i have NEVER EVER heard of that

you got issues.

20 yr old unit, converted to a new refrigerant (wonder how the compressor liked that?)

compressor is almost definately locked up, amp draw will tell the story. hitting it with a rubber mallet (really) may start it, but sounds like time for a new unit

I put in a new starting capacitor (har dstart kit) and now it has started with no problem and is working fine.

mattison: "I wouldn't put one dime into a 20 year old unit. Your throwing your money out the window."

haha


THANKS

We service one AC unit that is 39 years old. Have only put a new condenser fan in it is all HA HA

But most will die by 15 years TOPS.

Like the rest here just what is 22a ENVIROSAFE and did you change the oil?????? Hope its not LP like they tried to put in cars.

ED :D

Age isn't everything. If it had an hour meter on it you could get a better idea of how hard it had been used in 39 years. But not by looking at it. If you spent $15 bucks and it is running, you did the right thing.

Sorry Questi if you thought I was putting you down and the dime thing wasn't a literal 10 cent piece. Just that at 20 years old it's time to start planning for a new one. The one at my house is 25+ and still running strong with the original compressor and until it bites the dust it'll stay in there but I'm not going to sink 2-3 hundred bucks into it if something goes out.

Glad to see you got it running.