AC troubleshooting

[Dantheman1540]

@UmmScott last thing. Do I need to change anything in the rear ac system? I know it's all connected is there anything back there I need to mess with?

 

[UmmScott]

@UmmScott last thing. Do I need to change anything in the rear ac system? I know it's all connected is there anything back there I need to mess with?

The only thing would be the expansion valve. They normally will fail closed either due to a bad powerhead on the valve or get physically plugged up with debris.

Gotta open up the rear hvac box to get to it.

When you take out the condenser get a flashlight and look inside the open lines and look real carefully. Make sure theyre clean and that there isnt any buildup. Especially black sludgy looking things.
The discharge from the compressor will always have some debris in it but the line leaving the condenser should be clean.

If by some chance the line exiting the condenser and going to the split portion that feeds the front and rear units has debris or gunk in it, then i highly recommend flushing it out while you have the system open. As that could clog up your orifice and the exp valve in the rear.

But if lines look clean and just oily then you're good [emoji106][emoji106]

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[Dantheman1540]

The only thing would be the expansion valve. They normally will fail closed either due to a bad powerhead on the valve or get physically plugged up with debris.

Gotta open up the rear hvac box to get to it.

When you take out the condenser get a flashlight and look inside the open lines and look real carefully. Make sure theyre clean and that there isnt any buildup. Especially black sludgy looking things.
The discharge from the compressor will always have some debris in it but the line leaving the condenser should be clean.

If by some chance the line exiting the condenser and going to the split portion that feeds the front and rear units has debris or gunk in it, then i highly recommend flushing it out while you have the system open. As that could clog up your orifice and the exp valve in the rear.

But if lines look clean and just oily then you're good [emoji106][emoji106]

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Here is 3 swabs of the line exiting the condenser. Also some pictures of the various ports. Everything looks really clean to me.

Even swabbed the compressor and found nothing but oil.

 

[UmmScott]

Wow man!

Yes those lines look very clean! Green stuff is dye so all.good there...

Nice work man

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[Dantheman1540]

Should I blow the evaporator out with my compressor? I really don't want to put the dash apart.

Since everything looks clean does that mean it likely wasn't clogged and the compressor wasn't dying?

 

[Dantheman1540]

I guess I don't need to remove it. I can just blast cleaner in it and use compressed air to blast it out.

 

[Dantheman1540]

Getting pissed I changed the compressor, condenser, orifice tube and drier cleaned all the lines and evap core which were basically clean besides a little oil. Also added exactly 11oz of oil like it says to.and yet it's doing the same thing. Not even 2 cans 24oz in and it's reading crazy pressures again.

I vacuumed the system for over an hour then let it sit while I ran to town for coolant and lunch and it didn't drop a single psi.

Wtf do I do now?

 

[Dantheman1540]

Well with only the front AC on pressures are normal and the air is cold. Turn rear on and pressures spike. I got 3 and a half cans roughly 43oz in it and it's cold. Need to go for a drive because it's probably close to 120* in my tin can shop right now.

I'm thinking rear expansion valve is clogged. Stand by for updates lol

 

[UmmScott]

Well with only the front AC on pressures are normal and the air is cold. Turn rear on and pressures spike. I got 3 and a half cans roughly 43oz in it and it's cold. Need to go for a drive because it's probably close to 120* in my tin can shop right now.

I'm thinking rear expansion valve is clogged. Stand by for updates lol

No i disagree...
Something else is wrong.

Heres the thing. The rear never shuts off. If the compressor is on, then the rear is on too.
Theres no physically stopping the refrigerant flow to the rear.
The only thing that happens when u turn it off is the blower shuts off.

While i am skeptical of those cans, unless you're seriously overcharging it then that head pressure its very unacceptable.
Is your radiator fan working?? Please double check that.
Also do you have electric or clutch driven fan(s)

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[UmmScott]

Another thing...

Did you get the CORRECT condenser?
Again. Parts are specific whether you have front or front and rear AC.
If you got a condenser for a front only AC system that will be a big problem

God i hope thats not the case for ya.

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[Dantheman1540]

Another thing...

Did you get the CORRECT condenser?
Again. Parts are specific whether you have front or front and rear AC.
If you got a condenser for a front only AC system that will be a big problem

God i hope thats not the case for ya.

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Haha so originally I did get the wrong condenser but I noticed Thursday and got ththe correct one for rear air applications.

So let me start off by saying everything works amazing now! Vent gauge in front and rear vent says close to 40* output and its 90*+ ambient.

Ok so the entire problem stemmed from a very odd coincidence. This is an 04 truck and was previously converted to Efans with OEM parts and customer wiring by the PO. Turns out the E fans have not been engaging due to a bad relay that was made in communist China!

I went for a short drive and the air was ice cold came back parked it but left it running while I cleaned up shop a bit only to find it hot again. Immediately checked the condenser and it was scorching hot which tells me either it's not getting airflow. Turned truck back on and noticed the coolant was also getting warmer than usual. Looked at fans and nothing. Traced wires which was a pain because the PO put the 05+ aux fuse box in and did a nice job running all the wires but didn't get the fuse box cover that has the extra little lid that's removable. So I had to pull the whole cover off to find a burnt relay which is a rare sight can't remember the last time I saw a burnt relay like this. Swapped relays fans popped on and at idle the coolant went down to 180s and the ac got ice cold again!

My theory is that the fans quit the day I noticed the air not working. When they quit the condenser got hot and caused pressures to spike in turn making the valve stem leak. Which then led me to believe the ac system was just low due to a leak and down the rabbit hole I went!

Pictures show the method used to add oil and how much smaller the condenser designed without the rear ac system is.

P.S. I don't want to sound like I'm bashing the PO because he did build a badass truck and I probably would have done the same thing with the fuse box if I couldn't find one.

Also shout out to @UmmScott seriously man I owe you for the knowledge. Come to Orlando and I'll buy you lunch sometime.

 

[Dantheman1540]

I may have wasted some money rebuild the entire system but now I know it's new and should last a long time.

 

[UmmScott]

Awesome.

I am GLAD you found the problem.

I had a hunch about your fans not operating correctly.
Good catch and hey.. now you have a like new AC system.
Im very happy that you let it vacuum over an hour and checked that it held for over an hour.
That is very annoying but is a CRUCIAL step.

Kuddos man [emoji106][emoji106][emoji106]

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[UmmScott]

No wait..

Dan is the man..
[emoji16][emoji16][emoji106][emoji106]

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[Dantheman1540]

No wait..

Dan is the man..
[emoji16][emoji16][emoji106][emoji106]

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My little harbor freight vacuum was getting hot after about 30 minutes of pumping I thought for sure it was gonna catch fire so I was actually misting it and had it in front of a fan! (Yes it had oil.)


It's funny when you build a system from scratch it's easy to check all the boxes. But when your trying to solve an issue and only following the little clues you've been given like a leaky valve stem it's so easy to miss the bigger picture. Just gotta slow down and rethink things sometimes.

Doesn't help that its hotter than a Minneapolis police station this week.

 

[Dantheman1540]

Uhg my ac troubles have returned. Last night AC worked great, this morning AC does not work at all. Heat works fantastic, blower motor works on all speeds front and rear but the compressor does not kick on. I stopped at auto zone on my way to work and swapped the low pressure switch on the drier in 5 minutes hoping that was it but no change. Then used a super ghetto multimeter I happen to have with me and checked the voltage going to the switch and got 3v (The multimeter does not show any decimals it so ghetto).

If the switch is getting power then the controller is ok right?

I also checked the fuse under the hood and no change.

 

[Dantheman1540]

Swapped relay with the Hibeam relay and still nothing.

 

[Dantheman1540]

Found a leak. FML this will be my third time redoing this AC system.

Anyone else ever have this line leak from here?

 

[PG01]

Found a leak. FML this will be my third time redoing this AC system.

Anyone else ever have this line leak from here?

View attachment 259367

Didn’t you pull the head on that side?

 

[Dantheman1540]

Didn’t you pull the head on that side?

Pulled both heads. Pulled compressor to get to the front cover bolt that hides under it. I guess it might have caused a stress fracture but that was almost 3 weeks ago that seems like a long time for it to leak.