92 ex pressure blowing caps off ac fittings

[trozei123]

A big thank you first of all to everyone on this site. You are all truly masters at knowing what is wrong with these trucks and how to go about fixing them.

Here is a new riddle to solve. I have had my 92 ex for a few years now. When i first got it, the ac worked fine. The maintenance book i found in the glove box showed t was a fleet vehicle at a college that took very good care of it. About a year after i had the ex, i was at my storage unit cleaning it up when i heard a pop and a whooshing sound coming from the engine bay. It sounded like the plug was pulled on an air mattress and all the air rushes out. The truck was running and the ac was on medium speed. After that day, the ac stopped blowing cold. I did some reading on here and determined that the refrigerant was too low and it needed a charge.

A few months after that happened, i decided to try to get the ac working again. The compressor never ever clicked on, so i figured the system was full on empty. I bought a 20 oz can with a gauge from walmart and filled it up. The ac was working fine again. I knew that i did not have the full 1.75 lbs in the system, but i did not want to gamble with a small can and trying to add in the last 2 oz. Several months after the fill up, the same thing happened. POP! WHOOSH! no more cold air. this time i took a look at the fittings and caps after watching a video pat goss from motorweek did about how the fittings are not the actual main seals of the ac system, but the caps themselves are as they both have o rings up inside. Sure enough, when i took the caps off, the o rings were completely gone. I also took both fittings off and found that those o rings were also damaged. I got another r134a retrofit kit, swapped out the old fittings, and put the caps back on. I didn't have refrigerant in yet, but i figured when i did get it in there, it would actually stay in.

A few more months pass, and my fiance's old man brought home a small can about 3/4 full of refrigerant. After getting the adapter to hook it up to the gauge, i added it to the system. i was hoping it would be enough to at least get the compressor to kick on, even if it would shut off a few seconds later. It did. I was feeling lucky. But that left a new problem, i did not know exactly how much was in that can. About two weeks ago, I bought another small can so I could finish filling up the system. I had the can screwed on for not even two seconds, and the compressor started running without shutting off. the pressure on the gauge showed around 35 psi. I figured that was a little low since it was around 95 degrees outside, so i screwed the can on for another few seconds. pressure read 45. I decided that should do it. I estimated i had used barely any of the 12 oz in that can. A few hours later, as i was heading back to return the can for the ca core charge, i had the air on for only a few minutes when i hear the same thing. POP! WHOOSH! when i pulled into the parking lot and looked in the engine bay, i found that the high side cap was completely gone, and all the refrigerant had sprayed out over the power steering pump. I was fuming mad.

I figure i would do things the correct way and purchase a set of ac gauges and vacuum pump to suck the system down completely and fill it up again. But before i do that, i would like a second opinion. Does anyone know if the system was overcharged at all at any point in this timeline? What could cause the pressure to blow the cap off and drain the system? I will not spend a penny until i can know for sure what is wrong. Thanks for all your help.

 

[Centaurious]

Your hoses are deteriorating inside and the particles have clogged the orifice, thus causing the over-pressure. Bite the bullet and replace all the hoses and orifice. Before this flush the condenser and evaporator with AC flush and compressed air. After this is done the system can be pumped down with a vacuum pump and if it holds vacuum it can be charged.

There is no shortcut here. When the hoses start going they all are going bad. Mine blew a hose in two when the orifice clogged up.

Best of Luck

 

[trozei123]

I will look at flushing the system next. I pulled the orifice tube to see how bad it was, and there was not much at all. That puzzles me since i expected to find the thing caked with flakes. Is there anywhere else the blockage could be besides the orifice tube?

 

[larrydd999]

We're likely overlooking a major issue. If someone bought a can of refrigerant at WalMart, it was R134a. Unless it's been modified (properly or cheaply) the vehicle came with R12, which is not available over the counter and hasn't been for over 10 years. The '94 Explorer was the first year to come stock with R134a (I have one). The two refrigerants do not mix or get along with each other. If you want to do things right, I recommend you peruse this site and other similar ones and learn how to do a proper R134a conversion. Just my $0.02.

 

[trozei123]

Maybe i will look some more. Im guessing the retrofit was done properly because when i bought my ex from the car lot, i found the maintenance log in the glove box. Car was a one owner, and part of a fleet for a college close by. They took very good care of it. If there was any isdue, it appears that it was done right and right away based on how detailed the log is.

I was browsing my haynes manual today (even though its not a great manual, at least its something), and one thing im curious about is the accumulator. Given that in the three years i have owned the truck, the system has been empty for almost all that time. The ac only worked properly for about two months after i bought it. My two attempts to fix it ladted only a day.

Could the accumulator go bad by being empty for so long?

 

[Glacier991]

Accumulators rarely "go bad". Get a gauge set and check out your pressures. Generally when things start going south you may need to replace or flush most major components. I am curious about your conversion. Schrader don'T pop open as a rule. The cap is not the seal, the Schrader down the neck is, just like a bicycle tire.

 

[trozei123]

Thank you all for the great advice. I will absolutely look into all of it. I just got a gauge set last week. The pressures are 0 on both. I read that that means the system is completely empty. I will try to rent a vacuum pump soon leaks.

I just got new schrader valves yesterday since the last blowout caused it to disappear along with the cap. If the orifice tube is not blocked, what else could cause a buildup of pressure to make the high side blowout? Could there be an issue with the compressor to make it blow? Correct me if im wrong, but does the normal path go from the evaporator to the compressor to the condensor? If so, maybe thats where i need to look since the high fitting is between condensor and compressor.

 

[trozei123]

Finally! Good progress made. I pulled the orifice tube out to see how plugged it was. There was only a few flakes, but nothing terrible. I just replaced it since it was only 2$. After a while of waiting, I finally rented a vacuum pump. Let it run for about 45 min, got a perfect vacuum. Let it sit with the pump off for 30 min to make sure it stayed in vacuum. No leaks.

Followed that up with 24oz of refrigerant. It took a while before the compressor finally kicked on. I was getting nervous because the low side built up to about 120 before it kicked on. I left it off for the drive home because I saw the high side read 0. Turns out I didn't open the coupler valve when I was filling the system. I thought both valves for the high side needed to be closed.

My question now is that the compressor is kicking on very intermittently. I hears clicking coming from the electrical connector by the low side fitting. As I wiggled it, the compressor finally would come on. If the connection moved even slightly, the compressor turned off and the clicking resumed. I pulled the connector apart and found both sides covered in green grease. Should I clean that out to try to get a better connection? Or does the grease have to be in there?

 

[trozei123]

Cleaned out the grease, but no luck. I'm pretty sure its the connector to the pressure switch that's bad since the locking tab on the top of the connector is broken off. I know I should go to the junkyard and find a new connector and splice it in. But I considered also seeing if I could splice in two female connectors if they will fit. Any thoughts if that would work?

 

[trozei123]

This is a headache and a half. Went to the junkyard and got two replacement connectors to use (never hurts to get a spare). Used some electrical cleaner to try to get that green grease out, but its slow going since its so sticky. The compressor does come on, but if the connector moves even a hair, it stops working and the relay just clicks. Is there a test for the pressure switch to see if its going bad? Can the switch be removed without evacuation of all the refrigerant?