Fix the A/C Myself or I'm I better off just paying a professional

[sehaare]

Hey guys,

I've done several searches and done some of the preliminary troubleshooting and I'm pretty sure at this point I'm going to have to open up the system and replace something and I'm wondering if it is worth buying the tools required to fully troubleshoot this and refill the system after I replace whatever needs replacing?

Here's whats going on

The Vehicle:
1998 Explorer V-6 SOHC with Manual Temperature Control

Symptoms:

The system has had a slow leak for years. I have had to add refrigerant just about every summer and it would blow cold for another season. Added it again this year and it didn't fix the problem.

What I've done so far (after reading other threads suggestions):

With the A/C in Max, I warmed up the engine and verified that the heater hoses to the Fire wall are not hot (no leak-by on the temp control valve)

I fixed my blend door problem years ago by putting a finishing nail through the shaft and have verified that with the heater on, adjusting the temperature dial does change the air temp (I believe this proves that the blend door is moving - but it doesn't prove that it is going fully shut).

With the A/C on Max, the clutch on the compresses is cycling on and off.

At this point all I have is a cheap pressure gauge that comes with the cans of refrigerant and I see the pressure on the Low pressure side cycling as the A/C clutch cycles.

What next:

I've got the ford factory service manual for the vehicle and it has the troubleshooting guide that shows all the expected pressures. So the next step would be to run up to Harbor freight and buy an A/C gauge set and see what pressures I'm actually getting.

My gut feeling is that in addition to the slow leak the years of adding refrigerant with sealant in it has plugged something (possibly the orifice).

I did a refrigerant conversion (R-12 to 134) on another car years ago at a shop that had the A/C equipment required to recover and draw a vacuum on the system so I know a little bit about opening up the system, but no longer have access to that equipment. So at this point I'm believe that I'm looking at having to buy the A/C guage set, a vacuum pump, a new reciever/drier, new refrigerant and oil before I even buy the new part plus my labor.

Would I be better off just paying someone else since I'd have to go out and buy the A/C tools

Sorry this is so long, but I hate when someone post and only gives half of the story.

Thanks
Steve

 

[BubbaFL]

If the compressor is cycling, the system is likely low on refrigerant. If you're looking for a cheap fix, you could try adding more and see if that helps.

Does your accumulator have a blanket wrapped around it? If so, pull off the insulation and see if it's rusted.

The question about buying tools vs. paying someone to fix it is purely personal preference - what do you have more of, time or money? You can probably buy all of the tools needed to fix it for less than the labor cost of paying someone else to do it.

 

[sehaare]

When it cycles the cheapo gauge that came with the refrigerant can goes up into the red. I'm sure that is not good, but I think it also means that there is plenty of refrigerant in the system.

Could something downstream be plugged causing the pressure to build and the compressor possibly be cycling on over pressure?

I found this vacuum pump at harbor freight and I have a compressor that should have enough CFM to operate it.

http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

Not 100% sure of what all I'd need to do to refill the system if I have to open it up. Is there a procedure posted anywhere?

I would assume that I'd have to replace the part, replace the reciever/drier, draw a vacuum on the system, and then start adding cans of refrigerant.

I guess I should also try and find the original leak any suggestion on finding that (I don't really want to have to open the system twice and have to pay for twice the refrigerant?

Thanks
Steve

PS what part of Central Florida? I was stationed 3 times in Orlando back when it used to have a Navy Base.

 

[Sbyrne97]

The clutch on the compressor should cycle normally, unless it cycles very frequently you should not have a problem.

Heres where to look for leaks. At the hose's, the o-rings, and the ac condenser.

At the shop we use a UV dye to look for leaks...the dye is freakin expensive and requires a uv light to see.

but since your off on your own. I suggest you check your lines and check your fittings.

 

[BubbaFL]

Could something downstream be plugged causing the pressure to build and the compressor possibly be cycling on over pressure?

Could be, however, since you know the system has a leak, my first guess would be undercharged.

I found this vacuum pump at harbor freight and I have a compressor that should have enough CFM to operate it.

I haven't used one of those, but I've heard that they don't work very well. When I need it, I borrow a real vacuum pump from a buddy (looks like the $99 HF model).

 

[Lube]

Also, don't forget that if you have a refrigerant leak you also have an oil leak. You'll need to add some back into the system.
Harbor Freight also has a battery powered leak detector, which is much quicker to use than dye.

 

[sehaare]

The clutch on the compressor should cycle normally, unless it cycles very frequently you should not have a problem.

Heres where to look for leaks. At the hose's, the o-rings, and the ac condenser.

At the shop we use a UV dye to look for leaks...the dye is freakin expensive and requires a uv light to see.

but since your off on your own. I suggest you check your lines and check your fittings.

Has anyone tried using one of these dye kits?

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/PartSearchCmd?storeId=10151&catalogId=10051&langId=-1&pageId=partTypeList&suggestion=&actionSrc=Form&searchTerm=dye

 

[sehaare]

Also, don't forget that if you have a refrigerant leak you also have an oil leak. You'll need to add some back into the system.
Harbor Freight also has a battery powered leak detector, which is much quicker to use than dye.

yep but $80 for a one time use tool is starting to get steep

http://www.harborfreight.com/electronic-freon-and-halogen-leak-detector-92514.html


when you add that to the other tools that will probably cover about a hour and a half of Shop Labor.

 

[BubbaFL]

If you want to fix it right, you'll need to find the leak - check the accumulator first.

If that isn't it, you could take it to a shop that does a flat-rate diagnostic, let them tell you what's wrong, and give you a repair estimate. From there it's pretty easy to figure out what you would save DIY-ing and buying tools.

 

[sehaare]

Well. I broke down and bought the A/C gauges at Harbor Freight tonight, I'll have to wait until tomorrow to see what kind of pressures I get. Then maybe I'll be able to decide if I want to chase this any further on my own.

 

[BubbaFL]

Post the #'s when you have them - since it's cycling, try to get readings "right before" the compressor stops.

 

[sehaare]

Post the #'s when you have them - since it's cycling, try to get readings "right before" the compressor stops.

Here's the results, I haven't checked the manual values yet, I wanted to get them posted here first.

Ambient temp 88 degreess

Initial pressures with engine and A/C off

Low side 29# High side 31#

Pressures with A/C in Max and given time to steady out.

Low pressure cycles from 20# with compressor stopped to -4# at the end of the compressor run (I don't think that is should be drawing a vacuum).

High pressure cycles from 32# to 36# at the same time

The Compressor is running for about 1.75 seconds and is off for about 7.5 seconds


Also, the accumulator is covered with insulation and when I started to remove it, I saw a lot of rust underneath - so you might very well be right about this being the leak.

Thanks for the help
Steve

 

[sehaare]

Just did a quick check of the manual (I'm supposed to be working right now). I haven't found an expected static pressure value but I did see the following:

The A/C cycling switch (19E561) interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. it does this by monitoring the low side line pressure. it is known that a refrigerant pressure of approximately 30 psi will yield an operating temperature of 32 F. The A/C cycling switch controls system operation in an effort to maintain this temperature.

Since my low side pressure is always below 30# when the A/C is turned on, it appears to me that this switch is shutting off the compressor as soon as it tries to turn on.

So, I think that I need to find the leak, replace the bad part (probably the accumulator) and then refill the system.

Does that seem Right?

Is there a procedure posted for refilling the system?

I'm not sure about how to get the right amount of refrigerant and oil back in.

Thanks again
Steve

 

[Lube]

Does that seem Right?

Yes, it's cycling because there's not enough refrigerant to keep it running. Low side should not be in a vacuum

Is there a procedure posted for refilling the system?

Search the forum, you'll find lots of posts on it.

I'm not sure about how to get the right amount of refrigerant and oil back in.

Thanks again
Steve

There should be a label some where under the hood showing the required charge. You can get a little can containing 1 oz. of refrigerant and 2 oz. of oil, and that goes in just like a regular can of refrigerant. You'll need more refrigerant, but that will take care of the oil.

 

[BubbaFL]

Since my low side pressure is always below 30# when the A/C is turned on, it appears to me that this switch is shutting off the compressor as soon as it tries to turn on.

Static pressure should be much higher than that - IIRC, 80+ psi static around 90F would be closer to normal. Seems like your system is very undercharged.

So, I think that I need to find the leak, replace the bad part (probably the accumulator) and then refill the system.

Find the leak, replace the part. If it's the accumulator, you'll need spring coupling / fuel line disconnect tool to get it out, and new o-rings if your old one doesn't come with them.

Drain the oil out of the old accumulator and measure it - put that much PAG oil in the new accumulator before you install it.

I'd change the schraeder valves and o rings in the high and low side fittings while you have it apart.

Once you've done that, hook up a vacuum pump and draw a vacuum on it. This will let you know whether or not there are any leaks (if it doesn't hold vacuum, there's a leak). You'll want to draw as deep a vacuum as your equipment can, and hold it for a while - an hour or two should be good. The longer you do this, the more moisture you'll get out of the system and the better it will work.

After that, you're ready to charge the system. There should be a label under the hood that shows refrigerant capacity. I generally just use that as a guideline, and charge until I'm satisfied with the system's pressures and cooling.

When you charge the system, charge it through the LOW SIDE only. If you try to charge through the high side port with the compressor running, you could blow up your can of R134A.

 

[vipersinu2]

My A/C was leaking and I was hell bent on finding the leak, My last resort was the evaporator core, I removed the core from under the dash and air pressured tested the core in a bucket of water, it was good no leak or bubbles in water, reassembled and filled 134a and sprayed soapy water on the A/C Accumulator nozel and found the leak inside the fill nozel

replace the A/C Accumulator filled with 134a and at the same time blead the nozel on the other side of truck untill 134a came out the other side and have been fine for 3 years now.

 

[sehaare]

I've got to go out of town on business for a couple of day so this is going to have to go on hold for a while. I think that I'm hooked though and going to try and fix this myself.

I have 2 quick question though,

First, for both of the harbor freight vacuum pumps their manuals say to draw the initial vacuum with a recovery unit and then use the vacuum pump to reach the final vacuum pressure. I figure this is to recover the refrigerant. My question is, has anyone just used one of these vacuum pumps by itself to draw the full vacuum or would running the pump that long damage it?

And second an old timer (which I'm rapidly becoming) once told me that anytime you break open the A/C system you have to replace the Accumulator/drier as it will suck up all the moisture in the air. Is this still true if I find that after I attempt to fix the leak, I find that I still have another leak and have to open up the system a second time do I need to replace the accumulator/drier again?

Thanks
Steve

 

[scucci]

You can let the vacuum pump run as long as needed. The accumulator should be replaced if it had a blanket on it. Rust will eventually kill it. You would be wise to purchase an electronic leak detector and check for leaks while the system still has pressure on it. Harbor freight has an inexpensive detector that has some good reviews. Or rent one. The schrader port/valve cores tend to leak and must have caps with orings on them. I like to replace the schrader valves/port to prevent another near future leak. Fix all the leaks and then charge the system. Local walmarts and big lots sometimes have very low prices on r-134a refrigerant, as do Sam's clubs. You will need a can tapper. You need to look at the data label on the radiator shroud for the correct factory fill of r-134a and that is how much you put in, plus 1 to 2 oz. for loss in the hose/gages. The can of r-134a is 12 oz., not a pound. if the system calls for 2 lb, that would be 32 Oz. 2 cans plus 2/3 of a can. Oil must be added if any parts are replaced. Ford uses pag 46 oil. Pag is hydroscopic and will absorb moisture very quickly, do not open it until ready to use it. The parts you purchase will normally have a suggestion as to how much oil is added. You can drill a hole in the accumulator and measure how much oil comes out. If you have to open the system after replacing the accumulator you can plug the openings to keep out moisture so you don't need to replace the accumulator again. It is illegal to vent any refrigerant to the atmosphere. Here are some links to information you might want to read:
http://www.aircondition.com/tech/questions/27/A-Word-about-Safety

http://aircondition.com/tech/questions/82/Troubleshooting-with-Gauges-FAQ

http://aircondition.com/tech/questions/38/Air-Powered-A{47}C-Vacuum-Pumps

http://www.aircondition.com/tech/questions/68/Vacuum-Level-Required-to-Boil-Water

http://www.aircondition.com/tech/qu...d-to-Change-my-Receiver-Drier{47}Accumulator?

http://www.aircondition.com/tech/questions/15/What-is-Black-Death?

http://www.aircondition.com/tech/questions/95/Basic-Charging-Procedures

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=21372

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=7931

http://www.4s.com/Tech Resources-Tech Tips/Content.aspx

 

[BubbaFL]

And second an old timer (which I'm rapidly becoming) once told me that anytime you break open the A/C system you have to replace the Accumulator/drier as it will suck up all the moisture in the air.

That depends on how old the accumulator is, how long it was exposed to air, and what the outside humidity was. One that's been sitting in a empty system for a while should be replaced.

If you put a new one on there, and have to go back in later to fix another slow leak, I'd just pull it and tape up the ends while I did the rest of the job, and then reuse it. The key is pulling as deep a vacuum as you can, for as long as is practical, to minimize the amount of moisture in the system before recharging.

 

[sehaare]

thanks guys, I'll look the articles over tonight, as I gain more knowledge I'm getting more sure that I'm going to attempt this myself.


Thanks again
Steve