Got an 02 7.3 and I believe I over filled it with R-134a last night because after almost finishing off the bottle, freon shot out of the intake everywhere. It looked like I could have lost it all. Is there a low pressure shut off for the compressor? I removed a washer on the clutch because the plate spacing was stretched. So my question is, do I have to now have the whole system vacuumed and then refilled, or can I go get another bottle and fill it using the gauges I should have waited to use today? We put the low pressure gage and did not get a reading, but again the clutch was not engaging either. Any ideas? It was working last week and then just went to hot, so I pulled the clutch plate and a spacer, then filled but left it on to long. Hope that is descriptive enough

 

I don't understand about "shot out of the intake"
Did a hose blow,fitting fail?

If you didn't open the system,no need to pull a vacuum.

There is a low pressure switch,the pressureized freon will enter the system and trip the switch.(providing it is good)

If your gauges read 0, start the truck,add freon, the compressor should engage after the low pressure switch trips.

Best to hook up high and low pressure gauges.

(FYI - R134a systems are best charged by weight)

 

I was in the truck when the freon blew out. I think I over filled it to where the quick release hose to the R-134a can came off and somehow let a bunch release. I am not totally sure because I was just frantically running to turn the thing off. Everything looked fine after the fact thouhg. All the hoses intact and nothing out of order. I'll give it another shot and will keep the gauges handy to check

 

I started to add more freon with the gauges hooked up...the clutch now does not engage. It was the night before when I was puting in freon and it the freon went everywhere. Any idea on how to get the clutch going again? Did I blow a fuse or the low pressure switch? The pressure on the gauge fluctuates up and down, but still took the freon just no clutch engagement. Ideas?

 

The A/C clutch is controlled by the PCM via a relay. The PCM receives an input signal of +12v that comes from the HVAC control head, goes through the low pressure switch, through the high pressure switch, and then to the PCM. The PCM then grounds the primary side of the clutch relay, which is always fed +12v from a keyed source.

There are a couple of things I might do if I had your vehicle. First, make sure you have the correct amount of refrigerant. The only good way for you to do this at this point is bleed off the system and refill it with the proper amount or take it to someone with the proper equipment to do it for you. The charge amount must be accurate within a few oz or performance will suffer. At this point the low side pressure must be at least 42 psi to continue the tests.

Next, see if you can override the clutch relay by locating it in the relay box using the owner's manual, removing it, and with the key "on" jump the secondary side of the relay to see if the clutch engages. You can also verify you have power to the secondary side of the relay using a test light at this point. If you don't have power check the fuses and circuits feeding it. If the clutch engages when you do this, then the problem is somewhere on the primary side of the circuits, either the switches, the control head, the wiring, the PCM, fuses, etc. If the clutch won't engage with the jumper in place, check for power and ground at the clutch connector. If this is OK, then the clutch is bad. If you are missing either a power or ground, then you'll have to trace the circuits to find the problem.

Next, pull the connector off of the low side switch. The connector has spots for four terminals, but only two should be present. With the key "on" and the A/C "on" check each of these terminals with a test light. One should have power. If not, you need to backtrack the circuit and find out why. If you have power on one of the terminals, reconnect it and disconnect the high pressure switch. With the key and A/C still on, check the terminals there for power. Again, one should have power. If not, there is a problem with either the LOW pressure switch or the wiring between the LOW and HIGH pressure switch. If one terminal does have power, then you need to check the PCM at pin 41 for power with all connectors connected and the key and HVAC in the "on" position. If you have power there and all of the other checks are OK, then you may have a problem with the PCM. You'll need someone with a scanner that can monitor PIDs to check this out.

 

Whoa there. You're making this too diffficult. The main reasons the AC clutch doesn't engage (assuming the dash control is on AC...) is that the low pressure switch is not closed or the clutch gap is too large. He fixed the clutch gap already. That means in all likelihood the LP switch is not closing....which typically means you are low on freon.

So you probably need to charge the system again. If it is that low, then you should be able to dump a can into it with the engine off for sure. When it stops taking it passively, then you need to start the engine and use the compressor to draw it in. If it won't draw it in passively and won't engage the compressor clutch then you need to pull the LP siwitch plug and jumper it to fool the system into working until you get enough in there to let the LP switch work properly.

Now of course trhere are a lot of details to this, but if you start adding freon and it comes blowing back out somewhere, then you have a blow-off valve that is blown or not re-sealing. Or a massive leak.

Basically, try adding freon to it with engine off, and then jumper the LP switch plug once it stops taking it in passively. You really need a full set of gages to do this right, BTW.

If none of this works, then get deeper into this. But start with easy stuff.

-Dave

 

Ok I was thinking I am too low. After some thought, I think when I saw freon going out everywhere, it may have been the bottle spewing off because the valve was still open. Anyways, I will get another bottle and try to make it pull with the engine off. I have proper gages, although the high pressure connection is not holding the gauge on. Which is the LP switch(the connection on top of the compressor?) and how would you suggest to jumper it? I want to make sure I disconnecting the right thing.

 

Which is why the first thing I told him to verify was charge level.



The low pressure switch is located on the accumulator, which is the aluminum cylindrical device that has the low pressure fitting on it. The switch is next to it. Pull the locking tab on the connector and slide it off. Use a small, clean piece of wire to jump the terminals in the harness side connector. Be careful not to short it against anything else while it is there as it has +12v going through it.

Jay

 

Yep, and to clarify, the cylinder thingy he is talking about is on the passenger side, near the firewall.

Note one other thing that occurs to me in your case: If your system has been open to the atmosphere (i.e: it blew off everything) then it will not suck in any freon on it's own. You need to pump it down with a vacuum pump first. If you don't have one and aren't going to get one, then it might be best to take it to a shop and tell them to pump it down and fill it.

 

Ok that sounds manageable. I'll give it a shot and get back to y'all. Thanks for the help!

 

Also, I know it will suck the freon because I've done it but the clutch still does not kick on, so the air coming out of the vents is still hot. Could the fact that the clutch did not kick mean that I have over filled. Should I let some out so it will kick on? And if so how do I do that? I've put in about 2 1/2 cans since from the beginning of the process by the way.

 

Well with the blow off incident, you really have no idea how much is in the system. My '05 manual says 42 oz of refrigerant is required - that's 3.5 cans from empty. With no idea how much you lost, there's no good way to know how much to add, except to start fresh. Now you can probably get close enough as long as you have a real set of gages - depends how picky you are about the system performance. The high pressure cutoff switch is spec'd at 435-475 psi and the blow-off valve is at 550-600 psi (again, all from my '05). I would think you would have to have a major overfill to hit that cutoff.

You need to approach this systematically to solve it. Stop randomly adding freon: What are the readings you get from your gage set? You need to have at least about 25-30 psi on the low side for the LP switch to trip and close the clutch. If you don't have that, then you need to jumper the LP switch to get the compressor going. Once it is going it will suck in more freon. That is if you are low... If you are high, then you should see the high side reading in the range that would trip the HP cutout switch (see above).

Put the gages on it, get a reading with the engine off. They should both be 40-50+ psi at rest. Then start the engine and see if the compressor starts - again reading the pressures. If your low side is too low, then jumper the LP switch and the comp should start. Don't run it long this way - only when you are adding freon. Then you need to add freon until the pressures are in the right range for the air temp where the car is. There's a chart for that in the manuals.

-Dave

 

Ok so yesterday I bought a can of leak detecting R-134a. I put it in with the gauges hooked and the pressure went up to 15 on the low side and nothing on the high. The truck was off and it was taking the can fine. We did not see any leaks anywhere with very thorough searching. We jumpered the Low Pressure switch and the clutch kicked on. So seeing the pressure was consistent at 15, I figured we would put in more. So I drove to the parts store and got two more bottles. When I put the gauges back on, there was no pressure at all, both read 0. I can't find a leak, don't know what to do next.

 

You clearly have a massive leak. If it is beyond your abilities to track down and repair, you should probably find a decent shop to take it to. Sorry, but it sounds like this one is more than you can deal with, especially with only getting advice from a forum. If you have a friend or co-worker who knows a little about AC, then it would help a lot to have someone with experience get eyes on the issue. Otherwise, I think it is time to punt.

Sorry!

 

I pretty much have come to the same conclusion. Thank you for your help, it was very appreciated.