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A/C Help - Experts Inside Please Pages: 12

EverydayDiesel on Mon July 14, 2008 2:57 PM User is offline

Year: 2001
Make: Dodge
Model: Ram
Engine Size: I6D
Refrigerant Type: R134
Ambient Temp: 95
Pressure Low: 25
Pressure High: 275
Country of Origin: United States

For those of you that know, I have replaced the compressor, liquid line, condenser and drier all at the same time a few months ago. I pumped down the system with a 5fcm robinair pump and installed the proper amount of freon. The a/c worked for a few months until recently it got hotter and hotter.

My compressor was cycling on and off so I hooked up my gauges and added about 1/2 can of r134 to the system. The compressor stopped cycling so rapidly which was good but the a/c still blow hot. The gauges read 25/275 in 95 degree weather.

The condenser is getting hot. The liquid line that goes from the condenser to the firewall is hot towards the front of the truck and is ice cold (with condensation on the line) towards the firewall side. The other line coming from the firewall into the drier is normal (warm temp) the same as the actual drier itself.

What is happening? Is the box inside the truck plugged? Is this the symptoms of low refrigerant? What do I need to do to trouble shoot this further

EverydayDiesel on Mon July 14, 2008 3:26 PM User is offline

Heres a picture of whats going on. Im not that great of a graphics person....

bearing01 on Mon July 14, 2008 4:25 PM User is offline

When the compressor kicks in how long does it take to pull the pressure down? If you measure the time period from when the compressor kicks in to when it kicks in again, how long is that? And in that time cycle how many seconds is the compressor on for?

I would expect the bottom of the accumulator-drier to feel the same temperature as the blue line downstream of the orifice tube. Because it isn't, either the orifice tube is partially plugged or the system is low on refrigerant. In either case not enough liquid is fed to the evaporator and this is causing the refrigerant to quickly boil off and become a hot vapor, which is why that compressor suction line is warm and not cold.

Do you know if you have any leaks that would have caused you to loose refrigerant?

One check you can do is measure the liquid line temperature coming out of the condenser and compare that to the condenser's saturation temperature (the high side temperature read directly off the R134a gauge). The liquid line temp should be lower than the saturation temperature. Under heavy evaporator heat load if the system is flowing a lot of refrigerant (orifice tube not plugged) and if the refrigerant isn't backed up in the condenser at all then it may not be fully condensing in there. As a result the liquid leaving the condenser will be at the saturation temperature shown on the gauge. That means two things. 1) you likely still have vapor exiting the condenser along with the liquid and this will degrade performance. 2) #1 is happening because the system is low on refrigerant.

GM Tech on Mon July 14, 2008 4:28 PM User is offline

You are losing refrigerant- still needs more to work right-- sadlly, I highly suspect a leaky evaporator- have seen quite a few on Dodges- a good sniffer and some dye will confirm- look for dye at or around foam insulation at evap drain tube once you know you have dye in the system...

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Edited: Mon July 14, 2008 at 4:28 PM by GM Tech

EverydayDiesel on Mon July 14, 2008 6:18 PM User is offline

Quote
Originally posted by: bearing01
When the compressor kicks in how long does it take to pull the pressure down? If you measure the time period from when the compressor kicks in to when it kicks in again, how long is that? And in that time cycle how many seconds is the compressor on for?



I would expect the bottom of the accumulator-drier to feel the same temperature as the blue line downstream of the orifice tube. Because it isn't, either the orifice tube is partially plugged or the system is low on refrigerant. In either case not enough liquid is fed to the evaporator and this is causing the refrigerant to quickly boil off and become a hot vapor, which is why that compressor suction line is warm and not cold.



Do you know if you have any leaks that would have caused you to loose refrigerant?



One check you can do is measure the liquid line temperature coming out of the condenser and compare that to the condenser's saturation temperature (the high side temperature read directly off the R134a gauge). The liquid line temp should be lower than the saturation temperature. Under heavy evaporator heat load if the system is flowing a lot of refrigerant (orifice tube not plugged) and if the refrigerant isn't backed up in the condenser at all then it may not be fully condensing in there. As a result the liquid leaving the condenser will be at the saturation temperature shown on the gauge. That means two things. 1) you likely still have vapor exiting the condenser along with the liquid and this will degrade performance. 2) #1 is happening because the system is low on refrigerant.


before I added r134 it took about 1.5 seconds to go from 70 to 20.
the clutch cycled on very rapidly...maybe every 3-5 seconds on...then another 3-5 seconds off


after I added the 1/2 a can the refrigerant stopped cycling and the pressure stabilized to 25 on the cold side and 250 on the high side.
after a few minutes of running the high side rose to 275. inside the truck it blows hot as if there is no a/c on at all



Edited: Mon July 14, 2008 at 6:20 PM by EverydayDiesel

EverydayDiesel on Mon July 14, 2008 6:24 PM User is offline

Quote
Originally posted by: GM Tech
You are losing refrigerant- still needs more to work right-- sadlly, I highly suspect a leaky evaporator- have seen quite a few on Dodges- a good sniffer and some dye will confirm- look for dye at or around foam insulation at evap drain tube once you know you have dye in the system...

I just bought a new evap core. The truck has alot of miles so I will replace it plus its a pain alot of work to replace since I have to take appart the dash. I wish I had a way of measuring the refrigerant but unfortunately I dont.

NickD on Mon July 14, 2008 6:30 PM User is offline

Quote
The gauges read 25/275 in 95 degree weather.

At what engine speed did you measure those pressures at?

EverydayDiesel on Mon July 14, 2008 6:30 PM User is offline

Quote
Originally posted by: NickD
Quote
The gauges read 25/275 in 95 degree weather.



At what engine speed did you measure those pressures at?

idle.... its diesel so it only revs to 4k

Edited: Mon July 14, 2008 at 6:31 PM by EverydayDiesel

EverydayDiesel on Mon July 14, 2008 6:33 PM User is offline

I drained the new compressor free of oil...measured it and found it was a bit low so I added about 1/2 an ounce to make it 6.25 oz which is what the system calls for.
Because I put all the oil in the compressor when it was new, would that have plugged the liquid line?

NickD on Tue July 15, 2008 9:46 PM User is offline

Sure you can rev that diesel up to 1,500 rpm, AC on blower at max, a door open to give the correct pressures and noting those pressures at the ambient and RH conditions will provide a good reference for two weeks down the road or whatever to tell you if you have a leak.

HECAT on Wed July 16, 2008 10:03 AM User is offline

Quote
Originally posted by: EverydayDiesel
I drained the new compressor free of oil...measured it and found it was a bit low so I added about 1/2 an ounce to make it 6.25 oz which is what the system calls for.

Because I put all the oil in the compressor when it was new, would that have plugged the liquid line?

Probably not, but it does create another theory/opinion.

If previous system that failed was running low on charge, oil would have accumulated in the evap; unless I missed something about flushing, you added the full system load when installing the new compressor. The evap may have held 3 or 4 oz of old oil and now the system is overcharged with oil. This did not immediately present itself as a problem until you lost some refrigerant (leak). Now the evap is holding a large quantity of oil that is (1) causing poor cooling and (2) not migrating on because of low charge. Oil can be separated from the refrigerant by evaporation, therefore in theory enough refrigerant has to be supplied to the evap to create a substantial and chaotic boiling off of refrigerant to ("splash") migrate the oil out of the evap.


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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

NickD on Wed July 16, 2008 1:08 PM User is offline

Hecat, is that based on the theory that if a little medication or fertilizer is good, a lot more is much better?

HECAT on Wed July 16, 2008 2:44 PM User is offline

A little is good, a little more can be better, and too much can be bad.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

EverydayDiesel on Wed July 16, 2008 10:22 PM User is offline

Ok I found that my evap core was plugged. What a pain that was to remove and reinstall

My question now is...Do I need to add any oil to the system?
Of course I had to disconnect the lines and I dont have a recovery system so I will be adding 2.5 cans tomorrow
How can I measure how much I need to put back in, if any?

EverydayDiesel on Thu July 17, 2008 1:28 AM User is offline

Quote
Originally posted by: HECAT
Quote
Originally posted by: EverydayDiesel
I drained the new compressor free of oil...measured it and found it was a bit low so I added about 1/2 an ounce to make it 6.25 oz which is what the system calls for.



Because I put all the oil in the compressor when it was new, would that have plugged the liquid line?



Probably not, but it does create another theory/opinion.



If previous system that failed was running low on charge, oil would have accumulated in the evap; unless I missed something about flushing, you added the full system load when installing the new compressor. The evap may have held 3 or 4 oz of old oil and now the system is overcharged with oil. This did not immediately present itself as a problem until you lost some refrigerant (leak). Now the evap is holding a large quantity of oil that is (1) causing poor cooling and (2) not migrating on because of low charge. Oil can be separated from the refrigerant by evaporation, therefore in theory enough refrigerant has to be supplied to the evap to create a substantial and chaotic boiling off of refrigerant to ("splash") migrate the oil out of the evap.


I did flush the evap with chemicals before installing everything else. I also flushed the line that goes from the drier to the compressor. I used a/c cleaning chemicals to flush it.

How much oil do I need to add to the system since I replaced the evaporator core?

EverydayDiesel on Fri July 18, 2008 12:54 PM User is offline

can anyone tell me how I can tell how much oil I am suppose to add after replacing the evap core?

HECAT on Fri July 18, 2008 1:32 PM User is offline

I cannot tell you how much, but a guess would be about 2 or 3 oz. Wait to see if you get more guesses that may help you decide.

I have to ask, what clogged the evap after it was flushed a few moths ago?

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

EverydayDiesel on Fri July 18, 2008 3:20 PM User is offline

Its probably like you said before...evap core leaked refrigerant (it was very old) causing the oil to boil and plug the evap core. What else could it have been? The truck does have 200k on it.
I will check for leaks with UV dye when I go to fill it up. Plus the refrigerant I am using has leak seal that may help out in the future.

Edited: Fri July 18, 2008 at 3:22 PM by EverydayDiesel

HECAT on Fri July 18, 2008 4:31 PM User is offline

Sorry, leak seal answers my question. DO NOT use it.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mk378 on Fri July 18, 2008 4:57 PM User is offline

Never ever use leak seal. Here is another example of how it clogs stuff up on the inside. Clogging an evaporator is a pretty mean feat. Was your experience also that the leak seal was ineffective at stopping the leak to the outside?

The original Dodge evaporators were of low quality and leaked. A replacement from a reputable source will be different and will last the life of the truck.

EverydayDiesel on Fri July 18, 2008 6:41 PM User is offline

Ok I will take the leak seal back and get the regular stuff.

I did not use the leak seal before but I bought it this time thinking it would be better.
Its a good thing I did not open it. Thanks for the advice.

HECAT on Sat July 19, 2008 5:57 AM User is offline

Although the refrigerant is boiling in the evap, it is not generating the kind of heat that would cook the oil and clog the evap. It boils at a minus 15-20 degrees to carry away the heat load applied from the recirculating cabin air. If you have not used refrigerant with leak sealer before, then I am very happy we could warn you and you will exchange. However, this opens up the question again as to what has clogged the evap? Maybe if you get a chance, you could cut it open and post what it looks like.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

EverydayDiesel on Sat July 19, 2008 5:22 PM User is offline

I have exchanged the r134 for 3 cans of johnsens


I will cut it open and take pictures. I added 6.25 oz of pag150 which is what the system called for but I put all the oil inside the compressor.
The condenser, drier, compressor, and liquid line was new. I flushed the evapcore out with a/c cleaning chemicals. It may have been plugged before not plugged 100%.

I did buy the truck used and it has about 200k on it right now so who knows what the previous owner did to the a/c system.
Ill get some pictures of the core cut open.

Thanks everyone for the help...especially you HECAT

Edited: Sat July 19, 2008 at 5:25 PM by EverydayDiesel

vettman on Sat July 19, 2008 7:27 PM User is offline

Is "Everyday Diesel's" diagram correct? On my oem setup--Ford F350--the receiver/dryer "in" is connected to the liquid line coming out of the condenser (lower port), then from receiver/dryer to the evaporator. Compressor connections are: from evaporator outlet to suction side of the compressor, then high pressure gas outlet hose connects to the inlet (top) port on the condenser. No lines from the compressor are attached to the receiver.

Edited: Sat July 19, 2008 at 7:30 PM by vettman

HECAT on Sun July 20, 2008 8:50 AM User is offline

All the proper terminologies of receiver, dryer, filter, accumulator, etc.; get mixed up sometimes.

Filter device in high side line between cond and evap - TXV system (like your Ford).
Filter device in suction line after evap - OT system (like his Dodge).

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

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