Okay, despite all my bad luck with my 98 Expy, I still love this thing.

Here's the really odd thing. Last year I charged the AC system with that r134 stuff in a can and a gauge. Cool kit.

It worked for a year. Perfectly. Now it's summer so I decided to try my AC. Nothing. Must be needing a top off right?

Nope.

I checked the low pressure side and it was in the red band. Past the orange warning band and half way into the red band. Very Very bad.

How could it have overcharged itself? When I refilled it last year I made sure it was in the blue (good) band.

Now I just want to know how to fix it.

I expelled some gases out of the low pressure side to at least bring the band back to blue. Still nothing.

Any ideas? The compressor's clutch will not engage. I read on someones thread that you can jump a sensor or relay to make sure the clutch is at least working. The schematic didn't work though. Wrong site.

If anyone can tell me what to do next or bring up the old schematic, maybe even tell me where the ac relay is, it'd be great!

Oh yeah, all the fuses are good too.

 

Geez...

Don't take this personally, but your lack of knowledge about this system is amazing. Your reported actions indicate that you don't have the proper equipment or training to be poking around a potentially dangerous system.

If you've discovered an A/C system that magically makes more refrigerant than it started with, you've got a money-maker.

When the compressor is not engaged, the pressure in the system equalizes to what is called the STATIC PRESSURE. Depending on the temperature under the hood, this static pressure may be as much as 120 psi (hot day, hot engine) or as low as 30-50 psi (freezing day, cold engine). It all depends on the amount of refrigerant in the system and its temperature.

You just vented a (presumably) reasonably charged system below what it needs in order to energize the clutch and to operate. Now you have TWO problems: The original fault and now an undercharged system. We'll let the tree-huggers comment on the illegal discharge of refrigerant into the environment.

Your 98 does not use an AC relay. It's AC clutch is controlled directly by the pressure cycling switch fed via the high pressure cycling switch, and the MODE selector from fuse F5 under the hood.

Either the electrical circuit has failed (fuse or the cycling switch are most common) or your clutch has likely worn to an excessive gap (shouldn't exceed .030-.035 or so).

Next time, it might pay to ask first instead of being like a cave explorer who goes underground without lights, safety equipemnt, or a plan.

Steve

 

Ha ha, sweet. Yeah more pressure equals more money right? How come wallet isn't exploding.....

What happens when you have a leak in the system is the the pressure switch reads high. It doesn't necessarily mean it's making more refrigerant, just a higher pressure. This triggers the overpressure switch on the High pressure line.

I also made a boo boo on the type of refrigerant I had originally put in a year ago. I used 12A wich replaces 134A. 134A is what it originally came with wich is why I mixed them up. To my knowledge, this stuff is eco friendly .

Hope no tree hugger tries to have their way with with me, unless they're a chick. Hot chick.

The fix? Here's what worked for me.

Bleed a bit out of the High pressure side. Use a rag so the oils in the refrigerant don't get your eyes and do not inhale. This lets the overpressure switch on the high side see a lower pressure and then cycle the compressor.

When I did it, the compressor kicked in for about a split second and then out. The gauge would read high until the compressor kicked in and then it would compress until the pressure went low.

This is the normal cycle of low refrigerant. Then you simply add the R12A until it reads in the blue band of the gauge.

Done. That's what worked for me anyways. I know I could have gone to the shop to fix it and it can be dangerous to my health and it obviously wasn't the smartest thing to do. So don't try this at home........ I may have polluted the environment too wich has me feeling crappy right about now.

projectSHO89, I do thank you for your help and looking out for me as well as the environment.

Through me farting around with the system, I did learn how it worked instead of reading how it worked and scratching my bum all day.

Now when I have a problem with my trucks AC next year,

A: I won't have to take it back to the shop for them to repair it and keep me in the dark.

B: I just saved a bunch of ca$h ( $14.99 for a bottle )

C: I learned a bit about the refrigerant, the switches, fuses, compressor and pressures to service the system.

I realize there is a slow leak in the system, likely at the compressor because it's a bit wet. but let's face facts. It's going to cost at least $200 for a shop to get the compressor rebuilt or replaced, at least an hour labour and then the charge to evacuate and refill the system right?

What am I driving? No offense to anyone here cause I'm in the same boat. It's a F'n FORD. A 98. A decade old. These trucks used to be great back in the good old days but half the parts aren't even made in the US anymore. Gas prices aren't getting any better up here. $1.37 a liter today.

It doesn't make sense to drop cash into a truck that sucks fuel and has depreciated only to use a luxury like AC is all that I am saying. If it were the engine or trans being shot, fine. I can justify that. AC is an option. Newer Ford, different story.

This truck gets it's butt thrown through mud, hills, gravel, snow and rain. It's never let me down yet. Even when the GEM module went, I still drove it home in 4 by.

Point is that it's a bush truck not a pavement princess that needs to be on a hoist at the dealership to get her oil changed. A curb and a drain pan is all my truck asks for.

If there is a way to do it your self and it saves you $$$ then I am all for it.

 

A leak = high pressure? Yeah, sounds like you have that a/c stuff all figured out.

Reminds me of the decal on my toolbox at work:
We can fix broke but we can't fix stupid.

 

Where's that smilie for ROFLMAO??


Seems to apply.....

My sig on one of the other F150 sites is "Ignorance can be addressed through education but you can't fix stupid! ...apologies to Ron White"

 

"What happens when you have a leak in the system is the the pressure switch reads high. It doesn't necessarily mean it's making more refrigerant, just a higher pressure. This triggers the overpressure switch on the High pressure line."

This is what a certified Air conditioner tech at a place called richmond auto clinic told me. What he said may be wrong but it worked for me.

I know, you have a leak = less pressure.

Try and follow me here.....

The reason the reading was high in the first place at the low side is because my compressor wasn't cycling. ( Static Pressure ) When it does cycle, it brings the pressure down.

That was the whole reason I started this thread. To ask why.

The reason the compressor wasn't cycling is because there was too much pressure on the high side. ( Valve right by the high pressure cut out switch ).

I even jumped this sensor and watched the compressor kick in to prove that theory. That sensor trips when there is too much pressure.

That is why when I removed pressure from the High side, everything started to magically work.

This is what happened before I even had a chance to read the reply on this thread

I didn't mean to offend you guys but if I missed something, or a certified A/C tech is wrong, how about a little help instead of quoting stickers?

 

Wrong. The high pressure cutoff (HPCO) switch activates north of 300 psi, a figure unobtainable unless the compressor is operating.

Your static pressure should not have exceeded 120 psi on a hot day with a hot engine compartment. That means the pressure will read the same at both ports (and anywhere elese in the system).

When the compressor is not operating , the presure is the same at all points within the sealed system. Venting refrigerant can only reduce the pressure in the system if no other variables change.

Perhaps you have a defective HPCO switch. Nothing else would make sense.

Steve

 

What he said.
And since you vented some you now have an undercharged system. Not that it matters much anyways because from you posts I would assume it hadn't been properly charged in a long time.
As long as it works and you're happy with it I guess that's all that matters.

I would also suggest you find a new a/c technician. If he actually told you what you said he did then he can't even fix broke.

Try this. Next time you have a low tire create a leak (ie; stab it) and see if the pressure comes up.

 

So Steve,

From what your saying, wich makes more sense then the A/C tech and all laws of physics, when the system ( Sealed ) is off,

Low Pressure side equalizes with the high pressure side therefore the high reading at the low pressure side came from the residual off of the High pressure side during Static.

That clears a bunch.

So when the high pressure side got bled, it was NOT because I reduced the pressure in that line, rather that the switch being gummed, faulty or simply defective finally operared properly.

Thanks again Steve.

Since I'm being punished for asking dumb questions, what the heck right?

If I have a Hero all high on himself on one hand and I create a leak (ie; stab it's head ) Would the pressure in there still stay up to keep him on that high horse?

I mean it would have to right?

Unlike you, Just kidding Larry!

Cheers.

 

You didn't ask dumb questions. You just stated dumb answers that someone else gave you. I hereby redirect all my comments to that person.

 

I know. It still does make for a funny post.

 

Having some issues with ac , doing some research and stumbled across this hear. Blog and was walped with a reality check, wich i appreciate. Will now be taking my truck to ac guy qualified to carry out and diagnose my problem . My problem that i sure only make worse by going head first into cave with no lights or direction . Again thanks for that post you diffently helped me out .

Zackary dube

 

It's funny, I remember these posts when I was a newbie around here. Ahh, the good old days when the forums were a hoppin' place to be.