Compressor Testing?

[ma96782]

I've done a search.........but, haven't found an answer.

Don't mind me, if I use the words: accumulator and orifice as opposed to the other terms. It's all FRENCH.........but, you know what I'm saying.

So, question is: How does someone run a compressor test?

The shop where I take my vehicle to, has inspected and re-charged my Ac.............worked for about 3 weeks.

Took it back when I found a bad scherader valve. It was replaced and topped off. In about 3 weeks the Ac was warm again.

Took it back and this time, they found a leak in the hose, so it was replaced and new O rings installed (everywhere) re-filled w/ R-134a It worked for 2 weeks.

I took it back. They said it was still holding the R-134a, so they replaced the orifice tube and chemically flused the system. The orifice tube showed very little accumulation of fine particles metal dust size, not "the black death." Took it for a test ride and there is no cold air at all.

Now they say, it's the compressor and accumulator. I figure the accumulator is the original one and needs changing (BTW, it's not rusty). Though, I was wondering about the compressor (possibly the original one). I mean, how do I know if it isn't performing? I can hear the clutch cycle, on and off.

Yup, I have some doubts about the, "techs at this shop." Several different techs have been working on this, "problem." But, the owner is honest, and I trust him.

Comments please??

Aloha, Mark


PS...........What do you think: Bad tech work?? OR........Just Bad luck??

 

[BrooklynBay]

If you connect a manifold gauge set, you will see the pressure change when you cycle the A/C clutch. This will determine if there is pressure, and suction in the system.

 

[ma96782]

Thanks. Now, what kind of numbers should I be looking for?

Pass numbers

vs.

Fail numbers

Cause, I intent to ask the tech for the numbers. Before, I approve the replacement of the compressor.

Aloha, Mark

 

[BrooklynBay]

R134A will have a higher number than R12, so I think an average of 50 PSI on the low side should be average. It will vary while it is being charged (fluctuate higher, and lower). Check Glacier's thread on A/C A-Z. He shows a lot of gauge readings.

 

[BrooklynBay]

That thread is a sticky. Here is the link: http://www.explorerforum.com/forums/showthread.php?t=158183

 

[ma96782]

Thanks BrooklynBay,

I remember seeing that thread. Though, since the refilling of R-134a was done with the engine off........I didn't, "think" to look at it again.

FINAL: readings w/ the engine "on."........before being disconnected from the manifold.........28 psi low........240 psi high side.

Aloha, Mark

PS.............and I guess, that it will be different for different ambient air temps.

 

[BrooklynBay]

It is best to jump the compressor clutch while the A/C is running to fill it completely. The pressure probably varies in relation to altitude. I know this is the case when vacuumizing the system, and then reading the In of Hg.

 

[ma96782]

Of course a '92 uses R-12 and my '94 is a R-134a system. But, here is something else I found from Shamaal..........on another thread.

For a 92 Ford the pressures are 22-50/160-250 for LP/HP pressures; dependant upon temps and other factors.

Assuming that the pressure differential is there, as a minimum, the compressor is ..... compressing. It's possible that the compressor is marginal and there is a blockage (orifice). Also, we've seen a bad compressor clutch in another thread last week. So nothing is out of the question.

As, I've already changed the orifice tube and did a flush...........I'll really have to get those numbers from the tech.

Aloha, Mark

 

[shamaal]

For a 94 Explorer acceptable pressures are 22-50 on the low side and 160 to 250 on the high side. As you surmise, pressure will be dependant upon temperature and amount of airflow over condensor and evaporator. If you have >150 psi pressure differential I would say the compressor's compressing.

If it's leaking that's a different story. Look underneath the hood for a black line from left to right, that's a sign of a compressor seal breaking down, it throws oil.

The accumulator should be changed just from GP, the drier saturates.

It sounds like a slow leak, perhaps leak detector will work. I've always had good luck with it.

 

[BrooklynBay]

Freon is fed in as both a solid, and a liquid, so if your numbers are low, it might be from an insufficient charge in your system.

 

[BrooklynBay]

Here's a thread from Shamaal on how A/C systems work: http://www.explorerforum.com/forums/showthread.php?t=160498, and another thread from him with some pressure readings in relation to temperature: http://www.explorerforum.com/forums/showpost.php?p=1454068&postcount=18

 

[BrooklynBay]

Here's another post with readings from Shamaal: http://www.explorerforum.com/forums/showpost.php?p=1454238&postcount=20

 

[ma96782]

Speaking of numbers??

Is it correct to say..........36-45 degrees below the ambient air temps.

Aldive said, in another post:

.......with the thermometer probe in middle vent, he got

with ambient temperature at 96 F, the center vent with max AC set and the blower on the next to fastest setting, temperature is 54 F. This is a difference of 42 F.

(of course, my figures will vary slightly)


Aloha, Mark

 

[BrooklynBay]

A/C systems generally blow a temperature 40 degrees below the outside temperature when they are working properly.

 

[ma96782]

Thank you all for the help..........I have an appointment with the shop tomorrow.........so, I'll be ready.

Hope this will fix it.........once and for all. I'll keep everyone posted with an update.

Aloha, Mark

 

[ma96782]

******UP DATE**********

I went to the shop today........things went from BAD to WORST.

Besides the hi-side being "way low" on the gauge.........the evaporator showed leaking dye.......around the plastic housing that covers it, along the seam.

They wanted $660 to fix it (compressor, accumulator, evaporator and labor). Well I've already sunk $500 into it (inspection, re-charge, shreader valve, hose, orifice tube). Just wish, "I'd have known from the beginning." Then again, it could have been just my luck...........I guess.

So, I had them evacuate it...............and leave it.

I'll either end up changing the parts myself and have someone re-charge it, after I'm done.

Or

I'll leave it (drive with windows down) and/or trade the vehicle in (wife wants to update, anyway).

Thanks to everyone for their help. If I do buy parts and change it out..........I'll be sure to up date, again.

Aloha,Mark

PS.................If I decide to change the parts myself. Do I need to chemically flush the system, then add oil and re-charge it??

OR

Just add oil (as I put new parts on), then re-charge the system??

 

[ma96782]

Just finished checking on parts, not bad considering. FYI..........anyone looking for parts, try here:

http://www.ackits.com/

Aloha, Mark

 

[ma96782]

****I'm Gonna Do It Myself******

After finding the parts cost:

Compressor w/ clutch....................$204.33
Accumulator................................. 40.17
Evaporator................................... 58.14
O-ring kit..................................... 4.76
Nylog Lube................................... 6.90
8oz PAG 100................................. 6.50
UPS Shipping................................ 22.09

Total...........................................$342.89

I'm gonna try replacing the parts myself. Then, I'll take it to a shop for re-filling/service.


http://www.ackits.com/


I've just ordered the parts using the above web site.



Aloha, Mark

 

[shamaal]

A wise decision, you will also need the special tool for A/C fittings ($6)
Considering the total replacement, IMO, it's not necessary to flush. The only thing left is the condensor, and there doesn't appear to be any evidence it's bad.
Ask questions about anything you don't understand.

 

[ma96782]

Shamaal,

Mention "condensor"............ :fire:

Actually, I was smilin' cause, what else could go wrong?? . Oh Noooooooo.

Yup, thanks for the tool recomendation.................just gotta get down to auto zone.

Aloha, Mark