Engine A/C QUESTION

Mustang5L5 · May 5, 2026

The kit is great of you need one stop shopping, but you can likely grab all those parts, except the manifolds, from RockAuto for cheaper. They are pretty much the same brands they sell.

Accumulator will frost up depending on ambient conditions and this could be considered normal.

If you suspect your evap core is compromised, or even dirty internally, replace it. Would hate to see contaminates go downstream and plug up other components. Since AC work is expensive in general it's best to take an replace all approach to have the best luck of success.

I have seen folks remove the evap and flush it. You can certainly go that route to, but since it's out it wouldn't be a bad idea to replace it either.

NXcoupe · May 5, 2026

Noobz347 said:
Your [clutch cycling pressure switch] may be bad or intermittent (if it's shooting out of the relief valve):

Closes at 45 psi and reopens at 24.5 +/- 1.5 psi

V8 Foxes don't cycle the clutch. That is the low pressure cut off switch. It is there to protect the compressor from operating with not enough refrigerant in the system to move oil into the compressor. If your compressor is cycling, it's low on freon.

Mindseye007 · May 5, 2026

NXcoupe said:
V8 Foxes don't cycle the clutch. That is the low pressure cut off switch. It is there to protect the compressor from operating with not enough refrigerant in the system to move oil into the compressor. If your compressor is cycling, it's low on freon.

What if the compressor does not cycle at all ? Out of freon? Compressor cooked?

Mustang5L5 · May 6, 2026

Mindseye007 said:
What if the compressor does not cycle at all ? Out of freon? Compressor cooked?

If you jump out the low pressure cutoff, and the clutch doesn't engage it's likely electrical. Either the circuit of the compressor clutch itself. You'd have to check the wiring.

A properly charged system shouldn't cycle under most ambient conditions. Ambient temp has a huge role in system pressures and most situations where you run your AC should keep the low side pressure up high enough to prevent any cycling.

The only time the system may potentially cycle is if being used in cooler temps. Defrost for example on a 45-50 degree day. In this situation system pressures will be lower and the low side may dip under the min pressure to set off the low-pressure cutoff switch. This is exacerbated by the fact that many folks don't adjust the low pressure cutoff when they convert to R-134a and leave it at 25psi.

Mindseye007 · May 22, 2026

Mustang5L5 said:
If you jump out the low pressure cutoff, and the clutch doesn't engage it's likely electrical. Either the circuit of the compressor clutch itself. You'd have to check the wiring.

A properly charged system shouldn't cycle under most ambient conditions. Ambient temp has a huge role in system pressures and most situations where you run your AC should keep the low side pressure up high enough to prevent any cycling.

The only time the system may potentially cycle is if being used in cooler temps. Defrost for example on a 45-50 degree day. In this situation system pressures will be lower and the low side may dip under the min pressure to set off the low-pressure cutoff switch. This is exacerbated by the fact that many folks don't adjust the low pressure cutoff when they convert to R-134a and leave it at 25psi.

Ok trying to take my accumulator off there is that top big nut that conects to the evaporator and I used a Cresent wrench and it will not budge...this accumulator is 7 years old and it leaks so time for a new one, how do I get it off. I'm going to do my heater core and evaporator core perfect weather to do it and it's my first time doing it so and i have watched alot of youtube videos on how to do it. And so far that dam accumulator nut will not budge. Would heating up the nut with a heat gun work to help it break loose?

General karthief · May 25, 2026

Yes, no flames.

Mustang5L5 · May 26, 2026

Pen fluid. Spray and let sit. Big wrench. No flames on a pressured system with flammable gas.

Mindseye007 · May 26, 2026

Mustang5L5 said:
Pen fluid. Spray and let sit. Big wrench. No flames on a pressured system with flammable gas.

whaT IS the best pen fluid?

Liquid Wrench Penetrating fluid?

View: https://www.youtube.com/watch?v=xUEob2oAKVs&t=560s

General karthief · May 27, 2026

Mindseye007 said:
whaT IS the best pen fluid?

Liquid Wrench Penetrating fluid?
View: https://www.youtube.com/watch?v=xUEob2oAKVs&t=560s

whatever you have on hand at the time

Mustang5L5 · May 27, 2026

I like PB blaster because it's what I have.

nickyb · May 27, 2026

Whatever oil you use ,try tapping the wrench with a BFH as this will shock the out of it and break it loose.
And by tapping I mean wack it like it owes you money.

Mindseye007 · May 31, 2026

Mustang5L5 said:
Pen fluid. Spray and let sit. Big wrench. No flames on a pressured system with flammable gas.

You need 2 crescent wrenches cuz there is a small nut behind the big nut, will it be under pressure? Pulled the botom ac line off the evaporator and I thought the freon all leaked our when it spayed out of the pressure relief manifold when it popped , cuz a tonne of freon sprayed out, man was I wrong when I pulled the line off it sprayed out scary stuff could have died. Should have had it checked before and had all the freon evacuated out . Is that expensive to get done? I just want the dam hvac box out so I can replace the heater core and evaporator. sucks not having no heat or A/C, but I do love crusing with the windows down to hear the exhaust sound so sweet. I'll get a mechanic to install the new lines and manfolds might even get a new compressor all from lmr and charge it up again.

Mindseye007 · Jun 21, 2026

Mindseye007 said:
You need 2 crescent wrenches cuz there is a small nut behind the big nut, will it be under pressure? Pulled the botom ac line off the evaporator and I thought the freon all leaked our when it spayed out of the pressure relief manifold when it popped , cuz a tonne of freon sprayed out, man was I wrong when I pulled the line off it sprayed out scary stuff could have died. Should have had it checked before and had all the freon evacuated out . Is that expensive to get done? I just want the dam hvac box out so I can replace the heater core and evaporator. sucks not having no heat or A/C, but I do love crusing with the windows down to hear the exhaust sound so sweet. I'll get a mechanic to install the new lines and manfolds might even get a new compressor all from lmr and charge it up again.

finally done under the hood used needlenose vicegrips to grab the smaller nut and i got the big nut off with a cresent wrench im so happy. now its time to pull the dash out halfway like dover does in his heatercore removal and install, wonder if there i enough room to tackle and remove the evapourator core?

View: https://www.youtube.com/watch?v=AuuEFn-prIA

nicholase · Jun 21, 2026

You'll have to completely remove the plenum to replace the evaporator. Becasue you need to cut the case to remove it. At the factory they install the evaporator into one half of the plenum case and then glue the two halves together. So its sealed in there without an access panel.

Two methods,
Cut a flap on top. There is a molded in line you'll be able to see when you get the plenum out. Cut along it and make a flap. Replace evaporator and fold flap back. Black RTV or butyl the flap shut. A few self tappers to hold it while it sets up. Make sure its sealed up good. Let it dry before re installing.

Or alternately you can try and seperate the two halves of the plenum that are glued together at the factory. Trying to pry apart 40 year old plastic halves can result in cracks and causing more damage that it may benefit. So I don't suggest it.

IMO most poeple spend way more time on this job trying to not remove stuff than just pulling it out in the first place.

If you've never done it before (even of you have) get a notebook and write down what connectors you unplug and where they were located, what grounds you disconnect and where they were located, and what bolts go where. Ziplock baggies for bolts and screws, masking tape on the bag, sharpie where they came from. When you start putting it back together go through your notes and cross them out as you go. It sounds like alot of extra steps but I guarantee it makes it go way faster. "Pre-loading" 12 baggies w/ masking tape is a good start.

Tip. There are several types of "self tapper" style screws. They look the same, have the same size head, and lenght, but have different thread pitch. Pay attention to this. One style will thread into either. One will not. The one that will not will jam up and if forcefully turned will crack whatever plastic tab it's trying to attach too.

Don't be the guy with a pile of random screws sitting all over the interior and 8 "extra" screws when it's all back together lol

Bag and tag. Even if it's 2 screws in a bag "labled glove box trim panel / left side". And another baggie with 4 screws "upper dash to firewall". Or mark a few different size fasteners in one bag"(1) Dash speaker trim panel (2) speaker- left" . This will cut down on time and frustration GREATLY.

This is a pretty involved job so plan some time for it. Take your time doing it. You will then be successful.

I break it down into sections. An example is you know you'll have to remove the plastic dash trim under the steering column. Remove the fasteners bolts. Bag and tag in as many different baggies as possible. Remove the trim peice and set it with the baggies in a clean part of the garage. Move to the next thing and do the same way.

Good luck with it!

Mindseye007 · Jun 21, 2026

nicholase said:
You'll have to completely remove the plenum to replace the evaporator. Becasue you need to cut the case to remove it. At the factory they install the evaporator into one half of the plenum case and then glue the two halves together. So its sealed in there without an access panel.

Two methods,
Cut a flap on top. There is a molded in line you'll be able to see when you get the plenum out. Cut along it and make a flap. Replace evaporator and fold flap back. Black RTV or butyl the flap shut. A few self tappers to hold it while it sets up. Make sure its sealed up good. Let it dry before re installing.

Or alternately you can try and seperate the two halves of the plenum that are glued together at the factory. Trying to pry apart 40 year old plastic halves can result in cracks and causing more damage that it may benefit. So I don't suggest it.

IMO most poeple spend way more time on this job trying to not remove stuff than just pulling it out in the first place.

If you've never done it before (even of you have) get a notebook and write down what connectors you unplug and where they were located, what grounds you disconnect and where they were located, and what bolts go where. Ziplock baggies for bolts and screws, masking tape on the bag, sharpie where they came from. When you start putting it back together go through your notes and cross them out as you go. It sounds like alot of extra steps but I guarantee it makes it go way faster. "Pre-loading" 12 baggies w/ masking tape is a good start.

Tip. There are several types of "self tapper" style screws. They look the same, have the same size head, and lenght, but have different thread pitch. Pay attention to this. One style will thread into either. One will not. The one that will not will jam up and if forcefully turned will crack whatever plastic tab it's trying to attach too.

Don't be the guy with a pile of random screws sitting all over the interior and 8 "extra" screws when it's all back together lol

Bag and tag. Even if it's 2 screws in a bag "labled glove box trim panel / left side". And another baggie with 4 screws "upper dash to firewall". Or mark a few different size fasteners in one bag"(1) Dash speaker trim panel (2) speaker- left" . This will cut down on time and frustration GREATLY.

This is a pretty involved job so plan some time for it. Take your time doing it. You will then be successful.

I break it down into sections. An example is you know you'll have to remove the plastic dash trim under the steering column. Remove the fasteners bolts. Bag and tag in as many different baggies as possible. Remove the trim peice and set it with the baggies in a clean part of the garage. Move to the next thing and do the same way.

Good luck with it!

Thanks for the info also Check out how BREW2L does it pretty cool....

View: https://youtu.be/6pWnOLs2dWc

nicholase · Jun 21, 2026

^ yup. Thats how you do it. I used the same tool to cut mine. It works great. A Dremel or small cut off wheel would work too. The vibratory saw is super handy for lots of stuff. I use it all the time. The dash will basically be ready to pull out of the car, but it doesn't have to be physically removed. Just like his video. As long as it's floppy and loose and you can easily pull it back far enough to get the plenum out you're good to go.

Most people try and skip steps like the guage cluster connectors and stuff and then break in the effort to save time lol.

Its like getting a boy scout merit badge!
Heres mine:

General karthief · Jun 21, 2026

nicholase said:
Don't be the guy with a pile of random screws sitting all over the interior and 8 "extra" screws when it's all back together lol

Hummm, now who is "that guy"

Mindseye007 · Jun 21, 2026

nicholase said:
^ yup. Thats how you do it. I used the same tool to cut mine. It works great. A Dremel or small cut off wheel would work too. The vibratory saw is super handy for lots of stuff. I use it all the time. The dash will basically be ready to pull out of the car, but it doesn't have to be physically removed. Just like his video. As long as it's floppy and loose and you can easily pull it back far enough to get the plenum out you're good to go.

Most people try and skip steps like the guage cluster connectors and stuff and then break in the effort to save time lol.

Its like getting a boy scout merit badge!
Heres mine:

Did you change the evaporator core to?

nicholase · Jun 21, 2026

Mindseye007 said:
Did you change the evaporator core to?

Yup. I actually replaced the entire A/C system with a kit from Classic Air. Blows ice cubes.

Mindseye007 · Jun 21, 2026

nicholase said:
Yup. I actually replaced the entire A/C system with a kit from Classic Air. Blows ice cubes.

did you remove the plenum completly ? to remove the evapourator core'?

Engine A/C QUESTION

That is…until I whipped out my Bissell

Active Member

10 years still blowing strong

That is…until I whipped out my Bissell

10 years still blowing strong

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

10 years still blowing strong

Liquid Wrench Penetrating fluid?​

wonder how much it would cost to ship you a pair

Liquid Wrench Penetrating fluid?​

That is…until I whipped out my Bissell

I gotta say i never painted my nuts, Never Ever

10 years still blowing strong

10 years still blowing strong

I lubed and pushed, until it was all the way in

10 years still blowing strong

I lubed and pushed, until it was all the way in

wonder how much it would cost to ship you a pair

10 years still blowing strong

I lubed and pushed, until it was all the way in

10 years still blowing strong

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