A/C issues

[Itsgonnabreakforsure]

1997 tj 2.5l
Okay I’m stumped.
Replaced the following.
Ac condensor
Ac evap
Ac dyer
Ac compressor
Ac liquid line
Ac suction line

Pulled vacuum for 1.25 hours after pulling vacuum to -30 then letting it sit for over 45 minutes and no increases showing loss of vacuum.

Purged lines before refilling with r134a.
Went off weight and did 1.25lbs

High pressure side gets to 350psi
Low pressure side drops and compressor cycles off because it’s at 5psi and kills.

I reclaimed it at a local shop. Repulled vacuum and waited even longer in case there was an air pocket or something in the lines.

Repeated process to exact weight, and same thing. I’m scared to add more refrigerant I don’t want to over charge just in case high pressure switch doesn’t work…. It’s 90° here high humidity so I don’t know if I add more or what. Bypassed the low pressure switch to see if it will equalize and it didn’t just would keep dropping

Do I add more refrigerant since it’s an aftermarket system and have no real idea of what they call for or is there a restriction in the new parts that I just replaced…..

Let it sit rechecked, before starting low side was 80 and high was 100

Help please before I light this thing on fire.

 

[TJ4Jim]

1997 tj 2.5l
Okay I’m stumped.
Replaced the following.
Ac condensor
Ac evap
Ac dyer
Ac compressor
Ac liquid line
Ac suction line

Pulled vacuum for 1.25 hours after pulling vacuum to -30 then letting it sit for over 45 minutes and no increases showing loss of vacuum.

Purged lines before refilling with r134a.
Went off weight and did 1.25lbs

High pressure side gets to 350psi
Low pressure side drops and compressor cycles off because it’s at 5psi and kills.

I reclaimed it at a local shop. Repulled vacuum and waited even longer in case there was an air pocket or something in the lines.

Repeated process to exact weight, and same thing. I’m scared to add more refrigerant I don’t want to over charge just in case high pressure switch doesn’t work…. It’s 90° here high humidity so I don’t know if I add more or what. Bypassed the low pressure switch to see if it will equalize and it didn’t just would keep dropping

Do I add more refrigerant since it’s an aftermarket system and have no real idea of what they call for or is there a restriction in the new parts that I just replaced…..

Let it sit rechecked, before starting low side was 80 and high was 100

Help please before I light this thing on fire.

I have yet to charge a TJ with less then 24oz's of refrigerant working strictly with pressures. There is a pressure relief that will release on overpressure so no concern.

 

[swtrailboss]

No more refrigerant. 350 is WAY too high. Obviously 5psi is too low for the low side so I’m guessing your expansion valve has some issues unless that was included in the evaporator replacement. If so you likely have a damaged or clogged line.

 

[Itsgonnabreakforsure]

No more refrigerant. 350 is WAY too high. Obviously 5psi is too low for the low side so I’m guessing your expansion valve has some issues unless that was included in the evaporator replacement. If so you likely have a damaged or clogged line.

How would I go diagnose where the blockage is? I replaced the entire system, and just charged it yesterday, and then retried again today. Should I just replace the expansion valve and start there? Or is there a way to test where the blockage or damaged line is?

 

[sab]

High pressure side gets to 350psi
Low pressure side drops and compressor cycles off because it’s at 5psi and kills.

You definitely have something restricting flow if your pressure side is high and suction side is low.

...it’s an aftermarket system...

If it's an OEM-like system, it has a Fixed Orifice Tube (FOT) instead of an expansion valve. The FOT acts like a "throttle" that controls the flow rate of refrigerant in the system. This is usually the culprit because it doesn't take much debris from a compressor failure to clog it. However, if your entire system is new, it's likely either a manufacturing defect, dirt in the system, or an assembly error (pinching something) causing your problem. If your compressor is running 350psi and the suction pressure is just 5psi, I would expect you to be able to use compressed air to find the restriction. Disclaimer: I'm not an A/C technician, and I've never had this issue on any of my vehicles, so I'm not 100% sure that it will work. It's simply what I'd try if I encountered the same problem.

Have your shop recover the refrigerant again, The first thing I would look at is the FOT. Maybe something was dirty, and all that dirt ended up in the FOT. If so, you'll have to flush everything clean and reassemble. If the FOT looks like new, then you need to start disassembling the system and testing each component individually by running compressed air through them. My assumption is that one of them will not flow much air through it, and then you'll know where your restriction is. However, then you need to figure out if it's repairable or needs to be replaced.

Pulled vacuum for 1.25 hours after pulling vacuum to -30 then letting it sit for over 45 minutes and no increases showing loss of vacuum.

Purged lines before refilling with r134a.

What exactly do you mean here? Typically, you use this process to fill an A/C system:

1. Connect your gauge manifold to the pressure and suction lines
2. Connect the yellow hose to your vacuum pump
3. Evacuate the system
4. Let it sit and monitor the gauges to ensure it's got no leaks
5. Remove the yellow hose from the vacuum pump and attach it to your refrigerant tank
6. Charge the system

Above, you added a step somewhere in between 4 and 6 - "Purged lines before refilling..." What did you do to purge the lines, and what lines did you purge?

Went off weight and did 1.25lbs...Do I add more refrigerant since it’s an aftermarket system and have no real idea of what they call for

No, don't add more refrigerant because your symptoms don't match a low-refrigerant scenario. Does the manufacturer provide a charge weight? If it's a complete, turn-key A/C system, I would think they would. Can you contact them?

Bypassed the low pressure switch to see if it will equalize and it didn’t just would keep dropping

Another sign that you have a restriction.

Let it sit rechecked, before starting low side was 80 and high was 100

How long did it take for the low side to come up in pressure with it shut off? If minutes, rather than seconds, I would guess (again, I'm not an A/C tech, so I'm not sure) that you have a pretty serious restriction somewhere.

Repulled vacuum and waited even longer in case there was an air pocket or something in the lines.

Don't equate bleeding air out of a liquid-filled system (like brakes or the cooling system) with that of a gas-filled system. You don't have air (or gas) pockets in the A/C system when the pressure is at or below atmospheric. It's all gases (except for a small amount of condensed water vapor) that mix. As soon as you start pulling a vacuum, all the gases leave the system. Condensed water vapor boils back into vapor and leaves with the gases under vacuum. You run the pump for 30 minutes or more at max vacuum pressure to ensure all the condensed water vapor boils off, and the sole reason you leave the system under vacuum (pump off) for a period of time is to ensure you have no leaks.

 

[Itsgonnabreakforsure]

You definitely have something restricting flow if your pressure side is high and suction side is low.


If it's an OEM-like system, it has a Fixed Orifice Tube (FOT) instead of an expansion valve. The FOT acts like a "throttle" that controls the flow rate of refrigerant in the system. This is usually the culprit because it doesn't take much debris from a compressor failure to clog it. However, if your entire system is new, it's likely either a manufacturing defect, dirt in the system, or an assembly error (pinching something) causing your problem. If your compressor is running 350psi and the suction pressure is just 5psi, I would expect you to be able to use compressed air to find the restriction. Disclaimer: I'm not an A/C technician, and I've never had this issue on any of my vehicles, so I'm not 100% sure that it will work. It's simply what I'd try if I encountered the same problem.

Have your shop recover the refrigerant again, The first thing I would look at is the FOT. Maybe something was dirty, and all that dirt ended up in the FOT. If so, you'll have to flush everything clean and reassemble. If the FOT looks like new, then you need to start disassembling the system and testing each component individually by running compressed air through them. My assumption is that one of them will not flow much air through it, and then you'll know where your restriction is. However, then you need to figure out if it's repairable or needs to be replaced.


What exactly do you mean here? Typically, you use this process to fill an A/C system:

1. Connect your gauge manifold to the pressure and suction lines
2. Connect the yellow hose to your vacuum pump
3. Evacuate the system
4. Let it sit and monitor the gauges to ensure it's got no leaks
5. Remove the yellow hose from the vacuum pump and attach it to your refrigerant tank
6. Charge the system

Above, you added a step somewhere in between 4 and 6 - "Purged lines before refilling..." What did you do to purge the lines, and what lines did you purge?


No, don't add more refrigerant because your symptoms don't match a low-refrigerant scenario. Does the manufacturer provide a charge weight? If it's a complete, turn-key A/C system, I would think they would. Can you contact them?


Another sign that you have a restriction.


How long did it take for the low side to come up in pressure with it shut off? If minutes, rather than seconds, I would guess (again, I'm not an A/C tech, so I'm not sure) that you have a pretty serious restriction somewhere.


Don't equate bleeding air out of a liquid-filled system (like brakes or the cooling system) with that of a gas-filled system. You don't have air (or gas) pockets in the A/C system when the pressure is at or below atmospheric. It's all gases (except for a small amount of condensed water vapor) that mix. As soon as you start pulling a vacuum, all the gases leave the system. Condensed water vapor boils back into vapor and leaves with the gases under vacuum. You run the pump for 30 minutes or more at max vacuum pressure to ensure all the condensed water vapor boils off, and the sole reason you leave the system under vacuum (pump off) for a period of time is to ensure you have no leaks.

Manufacture bases it off oem system. I ran through every line and no kinks or anything.

I vacuumed the system and then purge the vacuum or feed line free of air with Freon before filling. Held vacuum, no signs of vacuum loss.

I just checked it again and start is 100 low and 100 high. Turned it on and same thing began to happen where it’s now only getting to 150 psi and then the low p/s kills compressor. So I’m stuck.

So it takes typically about 60 seconds for the sides to equalize sometimes less sometimes more. But the compressor will kick on for roughly 5 seconds then shut right off.

 

[RFAASRMA]

Is this the stock AC or an aftermarket? From my understanding they have different refrigerant weight requirements. 20 oz vs 24oz for aftermarket (I believe).

If it is an aftermarket it’s likely a Jeep Air and they provide the specs on their website.

 

[sab]

I ran through every line and no kinks or anything.

Then you need to start disassembling because it's likely dirt in the system clogging up somewhere. Again, I'd start by pulling the FOT and inspecting it.

I just checked it again and start is 100 low and 100 high. Turned it on and same thing began to happen where it’s now only getting to 150 psi and then the low p/s kills compressor. So I’m stuck.

So it takes typically about 60 seconds for the sides to equalize sometimes less sometimes more. But the compressor will kick on for roughly 5 seconds then shut right off.

All of that is indicative of a flow restriction. You're not stuck. Start investigating...

 

[williambmac]

Like others have said, you have a restriction and need to find it.

What was your original reason for replacing everything?

 

[Steve04]

Another thing to be aware of is if the system has too much refrigerant oil it can act as a restriction. Sometimes a new compressor comes with enough oil for the whole system, some will come without oil with a note to add oil

 

[Itsgonnabreakforsure]

Like others have said, you have a restriction and need to find it.

What was your original reason for replacing everything?

Did a complete overhaul, PO didn’t secure radiator properly and rubbed a whole into the low side line right off condenser. So I had to replace that, then while in process I noticed heater core was leaking so since I replaced that I replaced evaporator as well. Then I said well might as well test the compressor too, which was locked up, so I bought the whole kit from rock auto.

 

[Itsgonnabreakforsure]

Another thing to be aware of is if the system has too much refrigerant oil it can act as a restriction. Sometimes a new compressor comes with enough oil for the whole system, some will come without oil with a note to add oil

Is there a way to drain oil from the system or can a shop do that?

I did what the instructions said which was measure the 6.1oz from compressor, put 4 oz back, and 2 in condenser

 

[Itsgonnabreakforsure]

Is this the stock AC or an aftermarket? From my understanding they have different refrigerant weight requirements. 20 oz vs 24oz for aftermarket (I believe).

If it is an aftermarket it’s likely a Jeep Air and they provide the specs on their website.

Aftermarket system, all their specs said was follow factory spec, you know Chinese junk

 

[Steve04]

Service manual would have you remove compressor or condenser and drain the oil into something and measure it. Then figure that amount is 1/4 the total because the drier and evaporator are also holding some. Most guys would remove the easiest part and drain it, reinstall it without oil and see if the restriction is gone

 

[swtrailboss]

Your comment “compressor was locked up” tells me you likely have debris floating around in your system. Whether you call it an expansion valve or “FOT” fixed orifice tube it’s likely it has some debris clogging it causing the high side psi to be out of range. Definitely have your system discharged and flush out all solid lines and replace all rubber lines. Replace the expansion valve and go through the detailed recharge process you specified earlier and you will likely have this issue resolved. Unfortunately having installed all these new components before flushing the lines could create other complications or obstacles.

 

[Itsgonnabreakforsure]

Your comment “compressor was locked up” tells me you likely have debris floating around in your system. Whether you call it an expansion valve or “FOT” fixed orifice tube it’s likely it has some debris clogging it causing the high side psi to be out of range. Definitely have your system discharged and flush out all solid lines and replace all rubber lines. Replace the expansion valve and go through the detailed recharge process you specified earlier and you will likely have this issue resolved. Unfortunately having installed all these new components before flushing the lines could create other complications or obstacles.

Entire system was replaced. Not a single component is old. I even tore the dash out to replace heater core so I did the evaporation as well. Is a resto project. I’ll be tearing out components, blowing mild pressure through everything to blow any excess oil out, drain oil from compressor and start again.

 

[Steve04]

Something else you can try is with it running, use your hand or a digital thermometer to figure out where the restriction is. For example if top half of the condenser is hot and bottom isn’t something in the condenser is the issue. The temperature is going to be cooler beyond the restriction

 

[Itsgonnabreakforsure]

Something else you can try is with it running, use your hand or a digital thermometer to figure out where the restriction is. For example if top half of the condenser is hot and bottom isn’t something in the condenser is the issue. The temperature is going to be cooler beyond the restriction

Okay, I brought it to shop and had them reclaimed, I’m going to just replace dryer and the liquid line and see how that pans out. Thankfully I have a 12 month warranty on all this stuff

 

[Deputy Dodge]

If your gauges went from 350 to 150, I would look at the guages. I bought a harbor freight set that failed right out of the box. High side said 60psi when it was open atmosphere. Pull the orifice tube just for giggles if you want. My kit from jeepair specified 24 ounces and was perfect. Good for you purging the lines. Most people miss that step.

 

[Strizzo]

Maybe an obvious question but are you sure the fan/clutch is working and you’re getting good airflow through the radiator?

Did you flush the lines after replacing the components? You might have flushed compressor debris into the orifice tube crating a restriction as others stated.