A/C system - how to remove the cooling unit, evaporator, expansion valve (3 Viewers)

[CaptainNemo]

Thank you alia176 for engaging. You have a good point. I think your right. I think I'm missing something. It could be that I misdiagnosed the fluid coming out of a/c drain. My first concern arose several weeks ago with excessive a/c drainage. The engine coolant is leaking in the same area as a/c drainage but now I need to really take a closer look. The picture you show plus another one on this site would make it impossible for engine coolant to share condensation port. I therefore retract my previous thinking. I most likely have two seperate leaks going on and made an incorrect assumption. Excessive condensation in the same vicinity of engine coolant leaking from heater core. Thanks so much for challenging my statement. I needed it.

 

[bryson]

The rear heater lines run from the back of the head, over the transmission, and under the floor beneath the passenger seat. Those lines and associated pieces are awfully common to leak... A leak from them would present much like what you're describing too.

 

[cruiserdan]

The rear heater lines run from the back of the head, over the transmission, and under the floor beneath the passenger seat. Those lines and associated pieces are awfully common to leak... A leak from them would present much like what you're describing too.

All of that plumbing, with the exception of the rear heater core under the seat, is outside the passenger compartment. I'm not sure you would smell coolant in the cabin unless the rear core was leaking.

 

[alia176]

If you catch trays were under the engine then I'd venture to guess that the heater valve area on the firewall maybe leaking some coolant. This coolant is hitting the top of the bell housing, then snaking its way over to the passenger side of the vehicle. Which, coincidentally, is also where the drain hose is for the a/c evaporator. At this point, it's a WAG but look for pink goop on all heater coolant hoses and I bet something will jump out at you in the form of a loose hose clamp or something equally silly.

 

[CaptainNemo]

There is no visible leakage in the engine compartment that I have seen. I think the bell housing theory is most likely. If it is leaking and rolling over the bell housing where precisely might the leak originate? Is it possible to reach without pulling dash & instrument cluster?

 

[walleyefisher]

Thank you for this great pictorial walk thru

 

[alia176]

It's that time of the year when this thread gets bumped

 

[sjpitts]

I guess I will be the guy to bump this thread since it is supposed to be 117 here in AZ on Sunday. Ouch.

I have a late 93 with R134 and I believe I have a bad expansion valve. I have purchased a new denso expansion valve and a new denso receiver/drier from rockauto. I plan to follow procedure outlined in this thread to remove the evaporator, replace the expansion valve, reinstall the evaporator, and then replace the receiver drier. I am planning on getting new O-rings and Nylog blue for those O-Rings and PAG 46 oil.

My question is the amount off oil-- I am not sure how much oil to add back to the system. I saw that people said I needed to add this much oil when replacing these elements:

Evaporator: 40 cc (1.4 fl.oz.)
Receiver: 10 cc (0.35 fl.oz.)

But I also saw someone said to just add 10cc when replacing the Expansion valve, but I am not sure if that was in addition to or instead the evaporator oil amount. .
So basically I am not sure if I should be adding adding 40cc + 10cc or just 10cc+10cc for what I plan to do. Or maybe even 40cc+10cc+10cc.

Anyone know? Thanks.

Jared

 

[flintknapper]

I guess I will be the guy to bump this thread since it is supposed to be 117 here in AZ on Sunday. Ouch.

I have a late 93 with R134 and I believe I have a bad expansion valve. I have purchased a new denso expansion valve and a new denso receiver/drier from rockauto. I plan to follow procedure outlined in this thread to remove the evaporator, replace the expansion valve, reinstall the evaporator, and then replace the receiver drier. I am planning on getting new O-rings and Nylog blue for those O-Rings and PAG 46 oil.

My question is the amount off oil-- I am not sure how much oil to add back to the system. I saw that people said I needed to add this much oil when replacing these elements:

Evaporator: 40 cc (1.4 fl.oz.)
Receiver: 10 cc (0.35 fl.oz.)

But I also saw someone said to just add 10cc when replacing the Expansion valve, but I am not sure if that was in addition to or instead the evaporator oil amount. .
So basically I am not sure if I should be adding adding 40cc + 10cc or just 10cc+10cc for what I plan to do. Or maybe even 40cc+10cc+10cc.

Anyone know? Thanks.

Jared

Put an ounce in your Evaporator and an ounce in your Drier, call it good. You'll have lost a small amount also with the refrigerant evacuation. The oil is carried and distributed throughout the system by the refrigerant and is not required by non moving parts such as your Evap/Condenser/Lines anyway.

You don't want to be significantly under or over with your oil charge (total system) ....but an ounce or so either way is not that critical.

 

[sjpitts]

Put an ounce in your Evaporator and an ounce in your Drier, call it good. You'll have lost a small amount also with the refrigerant evacuation. The oil is carried and distributed throughout the system by the refrigerant and is not required by non moving parts such as your Evap/Condenser/Lines anyway.

You don't want to be significantly under or over with your oil charge (total system) ....but an ounce or so either way is not that critical.

So I went looking for 2 oz of PAG 46 oil, and I found this on Amazon. Each syringe is 2 oz, so I only need one, but it was only 9 bucks the same as one big bottle at NAPA. I am a little concerned that 3 of the syringes appear to have some air in them. So my plan is to use the one that didn't have air and put half in the evaporator and half in the new drier as you recommended. Unless you tell me that using this PAG oil is a bad idea for some reason.

Thanks again.

 

[MoGas]

So I went looking for 2 oz of PAG 46 oil, and I found this on Amazon. Each syringe is 2 oz, so I only need one, but it was only 9 bucks the same as one big bottle at NAPA. I am a little concerned that 3 of the syringes appear to have some air in them. So my plan is to use the one that didn't have air and put half in the evaporator and half in the new drier as you recommended. Unless you tell me that using this PAG oil is a bad idea for some reason.

Thanks again.

View attachment 2388310

You’re not injecting it. You pour it in at the connection and then close it up. The air bubbles won’t make any difference because you pull a vacuum prior to charging.

 

[ZackR]

Its good to be accurate but a tiny bit too much PAG oil isn't going to hurt anything.

 

[NexusD]

Awesome write up! thank you!

 

[Roocruiser]

I am UK based and R12 is illegal here, I am sure mine has had R134a in but its been left open and hoses off before I got the truck, I have got the dryer, condenser and compressor(rebuilt) and now just need expansion valve and evaporator. What do I need to do to ensure its clean before I recharge the system?

 

[MANUCHAO]

now just need expansion valve and evaporator. What do I need to do to ensure its clean before I recharge the system?

If you suspect debris in the system, then def replace the EV as it might get plugged up once you recharge the system.
If you have a shop do the work have the do a nitrogen sweep (couple of times) in the system and pull a good vacuum at 500 microns (29.92 hg) to get rid of non condensables.
Vacuum should hold without much gain / loss (decay test).
with that said now that you got the system half rebuilt I would get a new evap and EV and call it new !!!

 

[Roocruiser]

If you suspect debris in the system, then def replace the EV as it might get plugged up once you recharge the system.
If you have a shop do the work have the do a nitrogen sweep (couple of times) in the system and pull a good vacuum at 500 microns (29.92 hg) to get rid of non condensables.
Vacuum should hold without much gain / loss (decay test).
with that said now that you got the system half rebuilt I would get a new evap and EV and call it new !!!

What about all the hard lines? I will get a new Evap and ev abs yes I can get a shop to do it. Do I need loads of kit to do it myself?

 

[MANUCHAO]

when you pull vacuum or pressurize system with nitrogen.. It would show (you look and listen for leaks) the condition of the hard /rubber lines.....

 

[alia176]

@Roocruiser You can also download the pages from the FSM related to this project. It does a great job of detailing what needs to be done.

 

[Schmutz]

This thread saves the day again!

Today I successfully replaced the TXV and now have nice cool 39 degree air blowing out the vents I may add another partial can of refrigerant, which would likely bring it down further. First I want to wait for a proper hot day, and see how it performs with its current system charge...

I wish to tip my hat and thank @alia176 for your kindness in putting this thread together! Talk about a paint-by-numbers write up —even I could follow it. It gave me the confidence to tackle a project way beyond my comfort zone. Thank you to everyone else who contributed, and especially @flintknapper for all your assistance with diagnosis and pointing me to this thread.

 

[Schmutz]

On a technical note, I already confirmed that my compressor was performing well, and that my system was not suffering leakage. All symptoms pointed to a blocked TXV. @flintknapper confirmed symptoms. Therefore, I ordered the following from Amazon:
Denso Expansion Valve (part # 475-2005 —came with 4 O-rings)
Amazon product ASIN B01L03R0D0Denso Receiver Drier (part # 478-0503 —came with 2 O-rings)
Amazon product ASIN B000IWITNU4 Seasons O-ring kit (part # 26749)
https://www.amazon.com/Four-Seasons-26749-O-Ring/dp/B000C2O8V8

Also, purchased from a local auto parts store:
A bottle of PAG 46 oil with UV dye
A replacement Shrader valve kit. While the system is open, may as well eliminate that potential issue, right?
All up, about $78 worth of parts + three cans of R-134a

Upon removal my evaporator didn‘t look too bad...

I wondered where all the fluffy debris came from (there was a handful more in the bottom of the case, but I vacuumed away the evidence before it occurred to me to tie a photo )