At my wit's end with this air conditioner

[FixinDad1963]

My latest project began as a planned replacement of the a/c compressor, since the front shaft seal has been slowly leaking refrigerant, and was cause for an annual recover-vacuum-recharge.
I ordered and received a new compressor, liquid line, discharge line (with orifice tube pre-installed) & accumulator.
Installing these new items was unremarkable. I also flushed the condenser and evaporator core & purged the cleaner with compressed air until no residual cleaner was seen.

Then pullled a 45min vacuum that held overnight, then I refilled the system with1.25 lbs of r134.

Once completed, I ran the system with gauges attached on a very warm day (85-90 in the shade) low side pressure was 30-35 psi, high side @ 175 psi.

Underneath the hood, the system seemed to be functioning properly, but inside cabin, the temp was scanned at 62 degrees, while the discharge line temp at the firewall was 33.2F and the return line from the firewall to accumulator was 35.6 f.


Seems plenty cold to me when entering the firewall, but I would hope to see a higher temperature differential than 2.4 degrees after refrigerant passed through the evaporator.

No vacuum leaks, no issues with actuators. Lastly, I clamped off both heater hoses, to minimize speculation of blend door issues. All a/c & heat modes work properly. Blower fan is relatively new and works at all speeds.

All that to this: Before I dive into removing the dash and heat / air box from the firewall, is there anything I’ve missed?
Am I likely to find anything inside, such as a dirty and blocked evaporator?

What else can it be?

 

[D's Jeep Wrld]

My latest project began as a planned replacement of the a/c compressor, since the front shaft seal has been slowly leaking refrigerant, and was cause for an annual recover-vacuum-recharge.
I ordered and received a new compressor, liquid line, discharge line (with orifice tube pre-installed) & accumulator.
Installing these new items was unremarkable. I also flushed the condenser and evaporator core & purged the cleaner with compressed air until no residual cleaner was seen.

Then pullled a 45min vacuum that held overnight, then I refilled the system with1.25 lbs of r134.

Once completed, I ran the system with gauges attached on a very warm day (85-90 in the shade) low side pressure was 30-35 psi, high side @ 175 psi.

Underneath the hood, the system seemed to be functioning properly, but inside cabin, the temp was scanned at 62 degrees, while the discharge line temp at the firewall was 33.2F and the return line from the firewall to accumulator was 35.6 f.


Seems plenty cold to me when entering the firewall, but I would hope to see a higher temperature differential than 2.4 degrees after refrigerant passed through the evaporator.

No vacuum leaks, no issues with actuators. Lastly, I clamped off both heater hoses, to minimize speculation of blend door issues. All a/c & heat modes work properly. Blower fan is relatively new and works at all speeds.

All that to this: Before I dive into removing the dash and heat / air box from the firewall, is there anything I’ve missed?
Am I likely to find anything inside, such as a dirty and blocked evaporator?

What else can it be?

In your case you may have to add some more refrigerant, Im not an AC Expert but ill chime @freedom_in_4low since im sure he knows more about this !
I have about 42 psi on my low side in the shade at around the same temps, id like to add more refridgerant but im pretty happy with it so im not gonna bother.
Once its around 100* I get about 55 if i recall correctly. If anything i may add some more but again ill be alright! I know you're supposed to add a certain amount of refrigerant but in my case i did the 20 ounces it specifies but nope....too much id guage about 2 ounces that i recovered since my scale was iffy ! after i took some out it started blasting cold air, when its about 80* outside in the morning its too cold to the point i gotta turn it down so that says something, but in traffic in this hot texas heat its just cold not like my gladiator where i gotta turn it down a bit but she keeps me cool enough to where i'm happy
Edit- I cant spell....

 

[freedom_in_4low]

Seems to me like your pressures are on the low side.

This comes out of the service manual.

 

[D's Jeep Wrld]

In your case you may have to add some more refrigerant, Im not an AC Expert but ill chime @freedom_in_4low since im sure he knows more about this !

Seems to me like your pressures are on the low side.

This comes out of the service manual.

View attachment 540771

View attachment 540772

That was quick
Seconds after i mentioned you! Its like you spawned in

 

[freedom_in_4low]

In your case you may have to add some more refrigerant, Im not an AC Expert but ill chime @freedom_in_4low since im sure he knows more about this !
I have about 42 psi on my low side in the shade at around the same temps, id like to add more refridgerant but im pretty happy with it so im not gonna bother.
Once its around 100* I get about 55 if i recall correctly. If anything i may add some more but again ill be alright! I know you're supposed to add a certain amount of refrigerant but in my case i did the 20 ounces it specifies but nope....too much id guage about 2 ounces that i recovered since my scale was iffy ! after i took some out it started blasting cold air, when its about 80* outside in the morning its too cold to the point i gotta turn it down so that says something, but in traffic in this hot texas heat its just cold not like my gladiator where i gotta turn it down a bit but she keeps me cool enough to where i'm happy
Edit- I cant spell....

I know it's not your thread, but if your low side pressure is 55 at 100 ambient, adding refrigerant probably isn't going to help. I'd be checking the high side pressure and then refer back to the troubleshooting guide in the manual. You may have too much, or a dirty condenser. Would you buy chance have a cottonwood tree nearby?

 

[D's Jeep Wrld]

I know it's not your thread, but if your low side pressure is 55 at 100 ambient, adding refrigerant probably isn't going to help. I'd be checking the high side pressure and then refer back to the troubleshooting guide in the manual. You may have too much, or a dirty condenser. Would you buy chance have a cottonwood tree nearby?

Gotcha thank you!
What would a cottonwood tree do?

 

[freedom_in_4low]

Gotcha thank you!
What would a cottonwood tree do?

Cotton gets stuck on front of condenser and blocks airflow. I only bring it up because it's less obvious than mud.

To do it's job, both heat exchangers need surface area, airflow, and temperature difference. If you reduce one (such as by clogging it up with cotton, too much oil, or restrict the air flow with grill inserts), it will take more temperature difference to do the job, elevating the high side pressure. Too much refrigerant will do the same thing because liquid stacks up in the condenser and takes up surface area that should be used for condensing.

On the evaporator side, loss of airflow or low refrigerant causes low, low side pressure. Low charge reduces the liquid supply so its already mostly evaporated before it even gets to the evaporator and can't pick up much heat.

 

[FixinDad1963]

The cottonwood tree question is intriguing! If I’m picking up what you’re laying down, you’re suggesting it’s infamous pollen, along with similar debris, may have clogged the evaporator, and hence the air flow?

 

[FixinDad1963]

Cotton gets stuck on front of condenser and blocks airflow. I only bring it up because it's less obvious than mud.

To do it's job, both heat exchangers need surface area, airflow, and temperature difference. If you reduce one (such as by clogging it up with cotton, too much oil, or restrict the air flow with grill inserts), it will take more temperature difference to do the job, elevating the high side pressure. Too much refrigerant will do the same thing because liquid stacks up in the condenser and takes up surface area that should be used for condensing.

On the evaporator side, loss of airflow or low refrigerant causes low, low side pressure. Low charge reduces the liquid supply so its already mostly evaporated before it even gets to the evaporator and can't pick up much heat.

The condenser is clear. My hope here is to learn the likelihood of finding a clogged evaporator at the end of all the work to remove the entire heat & air box from the inside firewall. Is this likely?

It’s also been suggested that I shouldn’t have followed other advice by “flushing” the actual condenser. Is it possible the journals of the condenser coil may still have enough residual flushing liquid that my effective heat transfer capacity is diminished? In other words, what is the likelihood that my condenser effectiveness is compromised by either A) accumulation of cottonwood or other debris on the outside surface, or B) by residual flushing fluid still trapped on in the journals inside the condenser?

 

[FixinDad1963]

I understand the suggestions that my system may be slightly undercharged with r134, but I’d rather not admit that I succumbed to the temptation of “if adding a little more is good, adding a bunch more (of r134) is BETTER). No additional amount of refrigerant had any significant impact on the low-end pressure.
The system is back to 1.25 lbs of Freon.

 

[freedom_in_4low]

The cottonwood tree question is intriguing! If I’m picking up what you’re laying down, you’re suggesting it’s infamous pollen, along with similar debris, may have clogged the evaporator, and hence the air flow?

Condenser in the case of @D's Jeep Wrld, but in your case it would be the evaporator since the pressures look a little low. I mainly brought it up for him because his issue could be an occluded condenser and cottonwood finds it's way there quite easily. I hadn't thought of it for you because the path to the evaporator is a lot more complicated but the TJ doesn't have a cabin filter and the fan is easy enough to remove that it wouldn't hurt to check.

 

[FixinDad1963]

Here’s the thing, while my pressures are less than ideal, their not THAT bad IMO, and no matter what I do, I can’t get the dashboard output temp down, with my heater lines blocked, actuators working fine, great air volume

As I say, I’m at my wits end!

Thanks for the advice!

Stay tuned

 

[FixinDad1963]

Condenser in the case of @D's Jeep Wrld, but in your case it would be the evaporator since the pressures look a little low. I mainly brought it up for him because his issue could be an occluded condenser and cottonwood finds it's way there quite easily. I hadn't thought of it for you because the path to the evaporator is a lot more complicated but the TJ doesn't have a cabin filter and the fan is easy enough to remove that it wouldn't hurt to check.

Remove the blower motor and get enough access to see the evaporator coil? Excellent!

 

[freedom_in_4low]

The condenser is clear. My hope here is to learn the likelihood of finding a clogged evaporator at the end of all the work to remove the entire heat & air box from the inside firewall. Is this likely?

It's been a minute since I've been in there but I was thinking the evaporator was pretty close to the fan and you could potentially clean it from there. If not you could probably point your phone camera downwind and get a picture to see how it looks, and if you can't reach it to clean maybe use a leaf blower to back flush with air.

It’s also been suggested that I shouldn’t have followed other advice by “flushing” the actual condenser. Is it possible the journals of the condenser coil may still have enough residual flushing liquid that my effective heat transfer capacity is diminished? In other words, what is the likelihood that my condenser effectiveness is compromised by either A) accumulation of cottonwood or other debris on the outside surface, or B) by residual flushing fluid still trapped on in the journals inside the condenser?

If it held vacuum overnight then flush chemical shouldn't be giving you any trouble, as it would have evaporated under the vacuum and you'd have seen the pressure come back up as though you had a leak.

I don't think you have a condenser problem, because your pressures would be high.

 

[FixinDad1963]

I pulled the blower motor and took these photos with a handy ear scope.
It’s a little grungy, but not nearly as bad as I’d expected.
I’ll gently try to clean it and see if that makes a difference

 

[FixinDad1963]

BINGO!…I think…
Great tip to pull the blower for a look see! That allowed me to go back to square one, more or less.
As you sent in a screenshot, the factory service manual also directs me to the blend door. Not the various MODE doors…the Air Temperature BLEND Door, which is electronically actuated.
I removed the actuator motor and manually set the door so that no air would flow through the heater core chamber. Now I have 43 degree air coming out of the dash vents!!
As is typical, there’s a known problem and fix for the factory blend doors.
HeaterTreater
Thanks for helping me think through this one.
Stay tuned!

 

[swtrailboss]

Never saw in your thread description of the repair if you ever drained and measured the new compressor oil from the compressor prior to installing.

 

[FixinDad1963]

Never saw in your thread description of the repair if you ever drained and measured the new compressor oil from the compressor prior to installing.

6.1 oz came in the compressor.
Admittedly, everything else in the system was new (except the evaporator). PS-R1 oil is a new term for me, so I didn’t take the time to double check the PS-R1 oil volume, nor redistribute any of it to the newer components. Based on where I am today with the troubleshooting, should I still perform this exercise?

 

[swtrailboss]

Based on where I am today with the troubleshooting, should I still perform this exercise?

If you’re getting 43degrees at the vent and pressures are good then I would leave it seeing all components are new.