JeepMoreDoor

**If you think you can help with an AC issue please read. Thank you.

I hate to have to post this but a little help would be great. I just installed an almost everything new A/C system except for my evap. and condenser. I did clean them both with alcohol and blew them out with shop air. The new things are suction, discharge, liquid line w/ orifice tube, and the compressor which is a Murray brand from Oreilly. After install I recovered and vaccummed then charged, 1.25lbs refrigerant and I believe I added the correct 8oz?? I might be short...:/ The compressor seems to make a low vibrating kind of noise which is making me think it needs oil or I put the wrong oil (PAG 100). The compressor did have oil in it already so I assumed that oil was ok to use and just added dye to it. The liquid, suction, and accumulator get dripping wet like they should, but the A/C doesn't get as cold as I taught it would. I haven't checked with a thermometer but will do ASAP. I don't know if I need a bit more freon?? That's about it...the idle does get a little rough when ac is on. Any help or advice would be great. Again idk if noise is due to low oil, not that cold due to low freon, and if I got what I paid for on the compressor. Thanks again for all the time.

djb383

Did u install a new accumulator/dryer? IIRC, our new compressor (Orielly) had oil in it but we turned it upside down to drain the oil, as per the instructions, then installed the compressor. The FSM said 8.1 ozs total of PAG oil for the system so we measured and added 1/2 to the new compressor and 1/2 to the new dryer. 2 years later, thermometer still reads 34F at the center vents.

JeepMoreDoor

I did replace the accumulator. The compressor didn't have instructions so I didn't know if I was suppose to drain that oil or if I could use it. Is It too late to recover and drain the oil from it? I'm not sure how much has traveled through the system but I'd flush the whole thing all over again if I have to.

macgyver35

Hmm...

Did you add oil or freon first?

Adding 8 oz. of oil when the compressor already had oil in it may have been a bit much. I have a pic of the factory service manual recommended oil addition based on which components are replaced in my Cherokee album under my profile.

Rough isle with AC on? What are your pressures reading on the high and low side while running?

thakmfb

Is your electric fan working when the a/c is turned on? Do you have a set of gauges? If so what are the pressures reading? Hard to diagnose an a/c issue without knowing the pressures. Also if you aded too much oil to the system it will cause problems. If you did not drain the oil from the compressor and still added 8 oz I would think you have a little much oil. General rule is about 2oz. of oil for every component replaced.

JeepMoreDoor

The electric fan does kick on and I added oil first. I drained the compressor to see if it even had oil. It'd say there was about 4 oz. So I put it back. Then I added some to the accumulator and a small bit in the evap. I'm just wondering if that oil was just used to store the compressor so nothing rusted inside, and it needed to be drained and not used. Again, here weren't any instructions.

As for pressure readings I dont have guages, I'll have to post that Monday. I used the AC machine at work. If you guys want to keep up with the thread that would be great.

JeepMoreDoor

So the pressures while running was: low side 60psi & high side around 240. I know high side should be around there but low side should be about 25psi lower at 35. Help?! What are some causes for this reading?

djb383

Temp at center vent on max/recirc?

JeepMoreDoor

Didn't even bother. If I had to guess, 55-60? That's not cold!

lilredxj99

Need some more information. What year? Was it originally r12? How much refridgerant did the sticker indicate? Temperature and humidity?

If it was 90+* and hi humidity today, that reading might be acceptable.

There are more variables than just a gauge reading. You should also have the engine around 2000-2500 rpm to check the readings ... and the temperature at the center vent.

Also when you held a vacuum on the system did you hold it for at least 15 minutes?

djb383

Wonder if heater door could be leaking/not sealing? Since the dryer is getting cold, seems like the evap would also be getting cold.

macgyver35

Your low side pressure of 60 is not necessarily too high, and should not be down near 35. These systems have a low pressure cut-off switch that is designed to kick in at about 38 psi. Your readings will change based on ambient air temp.

I think you may have a bit much oil in the system, but unless it's WAY over the norm I don't think you'd see it hamper performance much. I could be wrong there.

When you vacuumed it down, did you take it all the way to at least 25 inches and hold it there for 10-20 minutes?

I'm also wondering if you might be suffering from a broken flap in the air plenum. If the control door that redirects to evap coils and heater core is not moving all the way to the full cold position you won't get good performance.

JeepMoreDoor

I ran the AC for about 1min and i heard a strange pop then smelt freon. The compressor shot out oil n freon thru the pressure relief valve. Does that mean I have to replace the valve?

BUT, it seems to be doing much better. I took off the compressor drained all the oil and blew it out with air. Then I drained oil from accumulator. Blew air thru condenser and evaporator. I think there was still alcohol in the evap. causing it not to get cold?? I'll never use that stuff again. I'll run the AC through out the week to see how it does.

Something I've noticed is it seems the compressor is always cycling. The clutch doesnt seem to disengage like my old sanden did. Anyone know what's going on there?

lilredxj99

The ac is a c c o t system. Clucth cycling orifice tube, when the low side pressure drops to about 30psi it kicks off. and comes back on again at like 50 psi. The constant cyclling could be too little freon, or it could be due to ambient temp...

You can get a low pressure switch that cycles at a lower psi than the oem one. If this was a r-134a conversion a lower cycling switch can make the vent air colder. I have also seen an adjustable switch.

The devil is in the details....

You do not have to replace the pop off valve.