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jmwilder1 on Fri May 02, 2014 9:20 PM User is offline

Year: 2000
Make: Dodge
Model: Durango
Engine Size: 5.2L
Refrigerant Type: R-134a
Ambient Temp: 95
Pressure Low: 25
Pressure High: 350

Hi all. I'm working on a 2000 Dodge Durango A/C system that I'm having issues with. First I will explain my procedure (for the pros so they can tell me if I did anything incorrectly), then I will explain the issue I'm seeing.

I recently replaced the blower fan motor, the compressor (new, not reman) and receiver/dryer bottle on this system. I poured PAG100 oil into both ports on the compressor prior to reconnecting the compressor lines.

On my manifold set, I started by first opening up both of the manifold valves and hose end valves to bring the manifold set to atmospheric pressure, then zero'ed the gauges to that. I then proceeded to connected the high and low side hoses to their respective service ports and the charge hose to a vacuum pump. I let the vacuum pump run on the system for about 10-15 minutes, then closed the ball valve on the charge hose and shut the vacuum pump off (ball valve is located on the can end of the charge hose) and let the system sit under vacuum for 1/2 hour.

The low side gauge registered greater than 30 in/hg of vacuum (needle was past the scale and down as far as it would go). After 1/2 hour the needed had not moved, so I decided to proceed with charging the system.

I closed down the high side manifold valve, then the charge hose ball valve. Then, with the charge hose valve closed, I disconnected the vacuum pump and connected a R-134a can with the blue can adapter and the tap valve on the top of the adapter. I then opened the tap valve fully, then the charge hose valve with the can upright to charge low pressure gas. I then proceeded to start the vehicle.

Vehicle AC running on max cool with blower fan on high speed and all doors/windows closed. The system took 2x 18oz cans.

At the time of charging I could not get the pressures above 165/35 at about 85* ambient temperature at idle. Today, at about 95*, pressures were 250/40 at idle and 350/25 at 2000 RPM.

The system, even though it's full, doesn't feel like it's getting as cold as it should and the pressures shown above do not look right to me at all. It does get cold, but it seemed like we had to run the blower at high speed at all times and the air coming out did not feel as cold as it should feel (unfortunately I did not have a vent thermometer to check the actual vent air temperature). Can someone tell me what issues would cause this?

Edited: Fri May 02, 2014 at 9:21 PM by jmwilder1

Jag987 on Sat May 03, 2014 12:16 AM User is offline

I will bite first.

Why was the compressor replace(failure, leak, wanted a shiny new one)? Was the expansion valve replaced? Was the system flushed? How much oil was added? Does it have rear ac? I would have ran the vacuum a bit longer, but the time that is was run may have been enough. The charging procedure sounds good, but leaves me scratching my head. It sounds like it was charger using small cans with a manifold gauge set, but 18 ounce cans? Besides death kits, I have only seen r134a in 12 ounce cans and 30 pound jugs.

Assuming it really was 18 ounce cans, and there was a loss of 2 ounces per can, there would be about 34 ounces in the system. The specs only call for 28 with front only ac and 32 with rear. Either way, it *might* be ok if the 34 ounce estimate is correct. The pressure readings are not what I would expect to see, at 2000 rpm's it is a high high, low low situation. Please answer the questions asked and it will help everyone figure this one out.

Thanks and welcome to the forum!

-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

Dougflas on Sat May 03, 2014 2:44 AM User is offline

350 on the high side is suspect. Is the condenser and radiator clean? Mist the condenser with a hose and tell us what happens to the pressures. I have had to replace condemser fans in the past.

jmwilder1 on Sat May 03, 2014 4:15 PM User is offline

jmwilder1 on Sat May 03, 2014 4:21 PM User is offline

Why was the compressor replaced?

Upon charging the system a first time, the clutch on the old one was slipping. We replaced both the compressor and the receiver/dryer bottle.

Was the expansion valve replaced?

No, but that was my next thought.

Was the system flushed?

The system was not flushed.

How much oil was added?

I poured PAG100 oil into the compressor prior to attaching the lines onto the compressor. It took about 1/2 of an 8oz bottle. No oil was charged into the system during the charging process.

Does it have rear AC?

Yes it has rear AC.

The system was in fact charged with a manifold set. However, the cans we bought came with their own charging hose/gauge, but these were discarded and not used. The can was connected to the manifold set using the standard blue can adapter with can tap twist valve.

mk378 on Sat May 03, 2014 7:01 PM User is offline

If the compressor was starting to break apart inside, the condenser is likely to have bits of metal from the old compressor clogging it up. This will cause an elevated high side and poor cooling.

Jag987 on Sun May 04, 2014 12:29 AM User is offline

First, thank you for answering all the questions asked. Doing that helps a lot, it is hard to diagnose something that is not in front of you.

Quote
Originally posted by: jmwilder1
Why was the compressor replaced?

Upon charging the system a first time, the clutch on the old one was slipping. We replaced both the compressor and the receiver/dryer bottle.

So the problems started with a system that was low on refrigerant? It was likely run low for some time. When this happens, the oil does not properly circulate and the compressor runs without oil. Yes, there is still oil in the system, but usually most of it ends up sitting in the evaporator where it does not do any good.

Quote
Originally posted by: mk378
If the compressor was starting to break apart inside, the condenser is likely to have bits of metal from the old compressor clogging it up. This will cause an elevated high side and poor cooling.

With what I just said, I agree with this. It is very possible that the compressor was coming apart inside and it has cause a partial block somewhere in the system. The system was not flushed, so we do not know what may be floating around inside.

Quote
Originally posted by: jmwilder1
Was the expansion valve replaced?
No, but that was my next thought.
Was the system flushed?
The system was not flushed.


More than likely, not replacing the expansion valve and not flushing the system has voided the warranty on the new compressor.
Quote

How much oil was added?

I poured PAG100 oil into the compressor prior to attaching the lines onto the compressor. It took about 1/2 of an 8oz bottle. No oil was charged into the system during the charging process.

Not knowing how much oil was in the compressor or dryer, this may be just fine. Considering it was not flushed and anything is a guess, this was a good guess. Again, if most of the oil was in the evap, any more than this would be too much.
Quote

Does it have rear AC?

Yes it has rear AC.

Knowing this, the amount of refrigerant is probably just fine.
Quote

The system was in fact charged with a manifold set. However, the cans we bought came with their own charging hose/gauge, but these were discarded and not used. The can was connected to the manifold set using the standard blue can adapter with can tap twist valve.

It was charged with a dyi kit, but with a real gauge set not the hose that came with it. The 18 ounce cans now make total sense to me. Besides r134, what else was in these cans (dye, stop leak, ect)?

My recommendations at this point would be to recover the refrigerant and remove the expansion valve. Check it close for signs of metal shavings/debris. Regardless, plan on replacing it. If metal is found, I would replace place the condenser and flush the hoses and lines. Do not flush the compressor and install another new dryer. Drain as much oil from the compressor as will come out. Then add back the correct total amount of oil called for placing half in the compressor and the rest throughout the system. Also, add some dye to the oil, it will help the next time there is a leak. Close it all back up and pull a good long vacuum and make sure it holds. At this point comes the big decisions. The best thing to do would be to take it to a shop that would be willing to recharge it for you ($). The next best would be to buy a scale ($$$) and a 30 pound jug or refrigerant ($$) and recharge it that way. My last choice would be to charge it with 3, 12 ounce cans of r134a, no fancy stuff with stop leak or anything else in it. This would be 36 ounces in a system that calls for 32, be everything from each can will not make it to the car.

I hope this helps and keep us updated. I hate it when the resolution is not posted. We never know what happened or if the problem was found and solved.

If anyone else has any other opinions, please share. I am here to learn as well and sometimes do not think about all the possibilities.


-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

jmwilder1 on Mon May 05, 2014 11:59 AM User is offline

Will do. We just ordered the expansion valves and 3x 12oz cans of standard R-134A with none of the above mentioned additives.

Thanks for all the help. A couple of questions -

1) Does anyone here happen to know where the expansion valves are located on a 2000 Dodge Durango?

2) After a system flush, will it be necessary to do an oil charge prior to charging refrigerant? If so, how much oil will be needed?

Edited: Mon May 05, 2014 at 5:52 PM by jmwilder1

jmwilder1 on Sat May 10, 2014 4:17 PM User is offline

Belay my last. I was able to locate both the front and rear expansion valves. The front expansion valve is on the passenger side of the firewall while the rear one is underneath the vehicle on the passenger side.

I will be doing the repairs today, then taking the vehicle in for a system flush tomorrow.

jmwilder1 on Mon May 12, 2014 3:02 PM User is offline

So I spoke with the local Pep Boys to set up an appointment for an AC system flush. One Pep Boys informed me that they will not touch the system unless they charge it up and will not just do a flush only. Another Pep Boys informed me that the only component in the system that would get flushed is the condenser, and that unless its a large tube condenser that it cannot be flushed and must be replaced if it is plugged.

On this vehicle, the high side service port is after the condenser and before the receiver/dryer. My way of thinking is that if the condenser was either plugged or had a restriction that the high side reading would drop rather than rise with an RPM increase, and in my case the reading is rising while the low side reading is dropping upon increase in RPM. Based on this, I'm thinking that the condenser is not plugged or restricted based on the location of the high side service port and the reading on the gauge.

The low side service port is directly on the compressor line fitting.

Based on this information, if one or the other expansion valve is restricted and/or closed that this would in fact cause a rising high side/falling low side reading as the refrigerant cannot flow through the expansion valve, which would cause a pressure build up on the high side while causing a pressure drop on the low side of the expansion valve. However, I am just a novice at this so please feel free to correct my thesis if it is incorrect.

Thoughts?

Edited: Mon May 12, 2014 at 3:03 PM by jmwilder1

mk378 on Mon May 12, 2014 4:17 PM User is offline

Modern condensers have multiple internal passages in parallel. Some of them can be clogged and refrigerant can still flow through one that is open. The problem is that when the refrigerant can't reach all areas of the condenser, it can't give off its heat and condense like it would in a good condenser. Thus the pressure rises -- not due to resticted flow, but due to inadequate condensing performance. The overall effect is the same as if the fan is not working(*), you will have abnormally high pressures on both ends of the condenser.

(*) The condenser fan(s) is/are working, right? Did anyone ask that yet?

Edited: Mon May 12, 2014 at 4:21 PM by mk378

jmwilder1 on Mon May 12, 2014 5:43 PM User is offline

Yes the condenser fan is working 100%.

jmwilder1 on Tue May 13, 2014 5:47 AM User is offline

So I went to replace the expansion valves today. Front one...no issues. Go to do the rear one...as it turns out they sent the wrong part! The part number on the box was correct, but the part in the box was not the same part that it was labeled as on the box.

Interesting thing is that it looked pretty much the same as what I removed from the vehicle, but one of the fittings was slightly too small to fit one of the lines and the mounting bolt spacing was just slightly off.

Another interesting bit...there was no gasket between the evaporator mounting flange and the expansion valve on the front unit on the one I removed. The new valve came with one though so it now has that gasket.

Called the supplier and they're overnighting another one. Hopefully I should have it ready to charge by Thursday.

jmwilder1 on Fri May 16, 2014 2:58 PM User is offline

OK...got the expansion valves replaced yesterday and charged the system. Pressures look lots better and both the front and rear units are blowing nice and cold.

I first pumped the system down for 1/2 hour, then waited another 1/2 hour with the manifold closed and pump off. System held vacuum so I proceeded to charge the system.

When I replaced the front expansion valve, a bunch of oil came out of the system. Since I only poured 3oz into the compressor when I replaced it, I decided to charge in 6oz of oil since the system holds a total of 8oz. I charged in 2x 3oz cans of oil first, with the cans upside down on the low side. I then charged in the first 12oz can of refrigerant as liquid on the high side. Charging in these initial charges took almost no time at all. Static pressures were showing roughly 80PSI. Once this was done, I proceeded to start the vehicle.

With the initial charge the compressor engaged on its own without me having to jump it. I then charged the 2nd and 3rd cans in as gas on the low side. System pressures at idle were about 180/45 with an OAT of 80-85*. At 2000 RPM, pressures were about 210/30.

Just heard back from my client and they stated that once the inside cooled down they could run the front fan on low and they were ice cold.

Jag987 on Fri May 16, 2014 5:05 PM User is offline

Glad we could help.

-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

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