2004 5.4L - A/C System Questions

[amish_electrician]

A/C compressor on my 2004 5.4L started making whirring sound (increased with RPM). Ruled out the clutch as the cause, so decided to play it safe and replace the compressor.

I don't wish this repair on anyone.

Drained oil from compressor, condenser and accumulator. Looked good... some dye, but no nasty black muck or metal debris. Think I caught compressor before it self destructed. Got the new compressor oiled and installed and then replaced the condenser and accumulator. Evacuated system for 1 hour. Holds vacuum... no leaks. My questions:

1) Since compressor had not failed catastrophically, I opted to just replace the compressor, condenser and accumulator. Didn't flush the lines or mess with the expansion valves or evaporators. Any opinions on this approach... good or bad?

2) While recharging the system with R134a, while shaking one of the cans, I noticed that the line connected to the can tap had become loose. (Harbor Freight manifold gauges... yeah, I know...) It hadn't loosened that much and I didn't hear any gas escaping. I hand tightened the line again and went about my business. What are the odds that air got introduced to the system? And if so, should I worry about it? Recover, evac and recharge again (being more careful)? Or am I over-thinking this one? A/C is nice and frosty cold by the way.

Thanks for any opinions or advice!

 

[stamp11127]

What are the pressures?

 

[amish_electrician]

If I recall... Low side - 30, High Side - 150.

Edit: I've read that these pressures are spot on for a Ford TXV system. It was around 72 degrees when I got these readings.

 

[stamp11127]

According to the "charts" it is a little low on refrigerant. I use the charts as a guide then tweak as needed. If the evap isn't freezing up I'd run with it keeping the evap just above freezing.

 

[Prince_Polaris]

On the subject of the 5.4L AC, is it true that I can fix both my not-really-cold rear AC and the hissing from the rear simply by adding more coolant to the system? Cause that's one of the limited things I know how to do!

 

[stamp11127]

Nope. See the stickies in the Heating & Cooling section on how the system works. Once you understand how the process works the troubleshooting is much easier.

Coolant is used in the engine cooling system - refrigerant is used in the HVAC system. Two completely different solutions.

 

[Prince_Polaris]

Nope. See the stickies in the Heating & Cooling section on how the system works. Once you understand how the process works the troubleshooting is much easier.

Coolant is used in the engine cooling system - refrigerant is used in the HVAC system. Two completely different solutions.

Yes, because I'm gonna pour radiator coolant into my AC line... you should know that on forums, reading threads that cover broad topics are never as good as asking people about your specific situations


Edit: Yeah, those threads might be helpful to someone else but those are all general AC troubleshooting (except the diagram of where the hoses go but that doesn't help me either)

 

[stamp11127]

The only thing about asking others for help very few actually know what they are talking about and may cost you a ton of money.

Read the threads, learn some things, then post facts and ask pertinent questions.

If you consider the 609 certification study guide "general AC" then you shouldn't need to ask anything on here.

Prince_Polaris, you stated the rear isn't cooling well. Nothing about the front not cooling correctly. These have 2 evaps, orifice tube in the front and txv in the back. If the front is fine, pressures are in line then there is a problem with the rear unit. You can check the txv operation with temp checks on the inlet and outlet lines to the rear evap.

 

[Prince_Polaris]

The only thing about asking others for help very few actually know what they are talking about and may cost you a ton of money.

Read the threads, learn some things, then post facts and ask pertinent questions.

If you consider the 609 certification study guide "general AC" then you shouldn't need to ask anything on here.

Prince_Polaris, you stated the rear isn't cooling well. Nothing about the front not cooling correctly. These have 2 evaps, orifice tube in the front and txv in the back. If the front is fine, pressures are in line then there is a problem with the rear unit. You can check the txv operation with temp checks on the inlet and outlet lines to the rear evap.

Jeez, even that is too complicated.... Perhaps I'll just save up money and tell a shop to look at it

So, considering that the rear AC hisses, perhaps it has a leak- does the rear AC have a line somewhere that I can hook up a can of refridgerant and fill it, then if it stops working later on I know it's messed up? I dunno, I want to learn the mechanical bits, but I also don't wanna break everything...

 

[stamp11127]

My advice now is, RTFM.....

 

[Prince_Polaris]

My advice now is, RTFM.....

You're not wrong tbh

 

[stamp11127]

It all comes back to the basics. If you know how the system operates and the components that are utilized then you troubleshoot problems instead of tossing parts at them.

So, is the front ac working correctly?

 

[1955moose]

Look Princey boy, would you just throw parts at an elaborate computer your working on, in hopes it might fix the customers problem? No of course not, you'd go through the regular diagnostic for the issue your customer was having, whether it's a total lack of power, or something more simple. Mechanical issues are really no different, theirs a flow chart. You start at symptoms and troubleshoot from there. You already have a leg up on some of our other members in that you have the electrical knowledge and can troubleshoot and read schematics. Like Stamp said read up on how air conditioning works, then you'll understand how to troubleshoot your system. You might want to spring for a Ford repair cd online, all will be on it!

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[stamp11127]

Bedrck47 is gone in body but lives on in spirit!

 

[1955moose]

Ain't that the truth!

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[stamp11127]

1955moose if one "Millennial" is getting under your skin you should try teaching. My class size is usually around 14 & most complain about spending $350 on a book - then state they don't understand it and refuse to read it. I point out we are only covering @600 pages in 12 weeks plus labs. What is the big deal? And you need to stay caught up.
Normally there are 2-3 students that are there to learn a trade so our time isn't wasted. The rest of them are for my entertainment....

 

[1955moose]

I actually get along pretty well with young men/women. The fact I'm 63 going on 18 doesn't hurt. The thing that drives me nuts though, is right smack in the middle of a conversation they have to see what's going on with their I phone. I had a young lady I was riding this morning on my bus, and I lost her 5 minutes into the conversation. I guess I turned into my father without realizing it!

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[Prince_Polaris]

It all comes back to the basics. If you know how the system operates and the components that are utilized then you troubleshoot problems instead of tossing parts at them.

So, is the front ac working correctly?

Yeah, sorry, I'm a bit strange, I tend to get frustrated with new things if I don't know everything right this second, it's a bad habit... growing up as a gifted child goes bad pretty fast because for years you don't need to study or do anything because you already know everything, and when your scope of knowledge suddenly isn't big enough, it's a disaster :/

-------------------------------

Anyway, yes, the front AC works fine. Since it was cold this morning, I tested the heat, and I do have working front and rear heat, thankfully, that will be nice this winter...

So, the front AC works, and surprisingly, it works best at highway speed, despite reports here on the forums about how highway speeds will make it stop working, due to the air pressure problem that you're meant to solve with an elbow... joint? I think that's it, the pipe thing.

The rear AC however, does not. It doesn't blow hot air, it's just simply not cold, like a fan you'd sit on your desk, it just blows the air. Also, there is a constant hissing from the rear when the AC is on, and it increases and decreases with what I assume is the fluctuations of the AC system.

It just confuses me, because... if it was a leak, a leak bad enough to hear the hissing, surely it would've leaked enough to stop my front AC from working, right? I read somewhere else on the forum (perhaps it was you, moose...) that if you're a bit low, the rear will stop working first, and all you need to do is add refridgerant to get it working again.

Normally, I would say something along the lines of "It's not that important because it's usually just me", however, our 07 chrysler van is once again broken, so I'm the family transport for now, and since me and my brother sit in the front, my parents aern't too happy with the nonfunctional AC, so I'm either hoping that it's an easy enough fix for me and my not-so-good-skills to fix, or that we can at least find out what's wrong so I can take it to a shop and save them from having to diagnose it themselves....

 

[stamp11127]

A good shop will take your input diagnosis then diagnose it properly so they only fix it once.

I'll go out on a limb here and assume you don't have the specialized equipment to needed to repair the ac. If you want to give it a shot though decent starter sets are around $400. And if the part I think has failed actually has, it is @$35.

If you have a leak, adding 134a is just a band aid.

 

[1955moose]

Wasn't me on the A/C diagnosis. Their is a valve and washers in the rear that go bad, I think that's what Stamps referring to. You have to pull apart passenger rear panels to access. You may have to have shop at least withdraw your freon, and possibly do repair.We warned you before you bought this Suv to have dealer fix all the loose ends before you took delivery. Well maybe that warranty they gave you will work.

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