Need guidance on 2002 Silverado air conditing

[mcj115]

Hopefully this question is appropriate for this forum. I have a 2002 Chevy Silverado 4.3V6 with ~260k miles. I have owned this since new so I know the history of the truck and the AC system has never been serviced, evacuated, opened or had refrigerant added. I am a DYI'er with moderate skills and manual HVAC tools. This is a 22 year old worktruck which a car wash could total, so I am trying to fix this cheaply (DYI) without unleashing the parts cannon.

Problem: AC doesn't work. The system hold refrigerant, how much volume I don't know. The compressor and clutch appear to be working, the kick on when I jump the terminals on the low side pressure switch. I own a cheapie interdynmanics "slam dunk" 134a kit with one gauge that fits on the low side port only. The gauge is NOT precision by any means. When I put on the gauge with the system static (engine running compressor not operating) has ~25 PSI; when I kick on the compressor by shorting the low side switch pressure crashes to near zero. Through my very novice troubleshooting I think it is either low on refrigerant or the low side switch is bad.
How can I determine if this needs the low side switch or more refrigerant. I could "rent" a set of gauges from a local parts store if needed. System capacity is 1.8lbs.

Any advise on troubleshooting further? Thanks in advance.
Mark

 

[BillK]

Mark,
I try to diy everything myself but when it comes to HVAC charging, especially on newer cars I just have somebody do it. I replaced almost the entire system on my 99 Tahoe about five years ago. When I was done i took it to one of my customers shop and had them vacuum it down and recharge it. It has been fine since then.

I think 134 is still pretty cheap, it might be worth trying to put a can in and see what happens. If you dont have any pressure it is probably low. If it was the switch the system would work when you jumpered it.

 

[Wrench97]

Static pressure as in truck not running ign off the pressure in either side should be pretty close to the ambident temp.
I.E, if it's 65f the pressure should be near 65 psi.
At 25 Psi the switch will be open not sending power to the compressor, that is how it should be.
So if it's 65 where the truck is parked and you have 25 Psi the system is low.
Total capacity is 1.8 lbs of R134a do not over charge the system.
Using the gauge charge until the low side gets to 40-45 Psi for temps between 60f and 80f with low humidity that should give you a outlet temp between 45f and 50f on max recirculate.

 

[AA/FC]

Wrench97 is correct. With a static pressure of 25 psi, the system is basically empty. That 25 PSI in the system would drop to zero almost instantly if you held the Schrader vale down. The system has a leak. The refrigerant went somewhere.

It's best to charge by weight. If the empty system holds 1.8 pounds, that is roughly 28.8 ounces... a small can of refrigerant is 12 ounces, which means the vehicle would require about 2.5 cans of R134a. Of course you may lose a little bit every time you connect (and bleed) a new can to the charge hose. Do not use refrigerant with stop leak. That is a great way to kill the system beyond affordable repair. You can use refrigerant cans with leak detection dye to help find the leak when the refrigerant leaks out again.

It's possible that factory refrigerant had green dye in it. Look for wet spots around all connections in the refrigerant lines going to/from the compressor, accumulator, condenser, etc, etc. and around the service port fittings. The spring loaded Schrader vales will start to leak over time. A leaky compressor shaft seal is also a good possibility. And of course, if all else fails, a leaky evaporator under the dashboard could be the culprit. If you can't find the leak, the system may hold refrigerant for a few hours, or a few months. It's hard to say without knowing where the leak is. To fix it properly, you should find and fix the leak first.... which isn't always easy without the proper tools. Good luck.

 

[75gmck25]

In the old days you could charge by pressure and watching for bubbles, but with newer systems it's now always done by weight. The machine is so automated that the guy running doesn't really have to do much but hook it up and pick the amount of refrigerant needed (out of a reference book). After that the machine runs on its own to recover the old refrigerant, vacuum it down to the required level, and push in the right amount of refrigerant.

 

[DGersic]

Hopefully this question is appropriate for this forum. I have a 2002 Chevy Silverado 4.3V6 with ~260k miles. I have owned this since new so I know the history of the truck and the AC system has never been serviced, evacuated, opened or had refrigerant added. I am a DYI'er with moderate skills and manual HVAC tools. This is a 22 year old worktruck which a car wash could total, so I am trying to fix this cheaply (DYI) without unleashing the parts cannon.

Problem: AC doesn't work. The system hold refrigerant, how much volume I don't know. The compressor and clutch appear to be working, the kick on when I jump the terminals on the low side pressure switch. I own a cheapie interdynmanics "slam dunk" 134a kit with one gauge that fits on the low side port only. The gauge is NOT precision by any means. When I put on the gauge with the system static (engine running compressor not operating) has ~25 PSI; when I kick on the compressor by shorting the low side switch pressure crashes to near zero. Through my very novice troubleshooting I think it is either low on refrigerant or the low side switch is bad.
How can I determine if this needs the low side switch or more refrigerant. I could "rent" a set of gauges from a local parts store if needed. System capacity is 1.8lbs.

Any advise on troubleshooting further? Thanks in advance.
Mark

You have a leak. And an old system. My experience with my old truck‘s A/C is that the parts cannon will be fired at it. You’ll probably find the leak at the evaporator, that’s buried under the dash. Replace that, and the compressor will **** out when you charge it. Get a new compressor, plus the accumulator and expansion valve. Rinse out the system. Charge it, and hope that the Schraeder valves and O rings don’t fail (they will). You may save the condenser and lines, maybe. I’ve had lines fail too.

Minimally, you need a set of gauges, and a vacuum pump. For leak hunting, you should get a tank of nitrogen. Ideally, a scale and a recovery setup would be used to keep the R134a out of the atmosphere, but with a leak there may not be anything to recover.

 

[rustedgoat]

I had best results with starting with an empty system, checking for leaks with a vacuum pump and using a dual gauge set when adding refrigerant by weight (all cheap harbor freight stuff).

 

[mcj115]

We had a warm enough day recently, so I added some R134 to the system it seems to be working well, for now at least. The system didn't even take a full can..so it wasn't totally empty; maybe just a little low .
Now time will tell if the system will hold. I want to try the "east route" at least once before getting into a complete system overhaul.

 

[captaindiode]

The seals on those compressors are prone to leak. Especially that old

 

[jesse b >pepper<]

Hopefully this question is appropriate for this forum. I have a 2002 Chevy Silverado 4.3V6 with ~260k miles. I have owned this since new so I know the history of the truck and the AC system has never been serviced, evacuated, opened or had refrigerant added. I am a DYI'er with moderate skills and manual HVAC tools. This is a 22 year old worktruck which a car wash could total, so I am trying to fix this cheaply (DYI) without unleashing the parts cannon.

Problem: AC doesn't work. The system hold refrigerant, how much volume I don't know. The compressor and clutch appear to be working, the kick on when I jump the terminals on the low side pressure switch. I own a cheapie interdynmanics "slam dunk" 134a kit with one gauge that fits on the low side port only. The gauge is NOT precision by any means. When I put on the gauge with the system static (engine running compressor not operating) has ~25 PSI; when I kick on the compressor by shorting the low side switch pressure crashes to near zero. Through my very novice troubleshooting I think it is either low on refrigerant or the low side switch is bad.
How can I determine if this needs the low side switch or more refrigerant. I could "rent" a set of gauges from a local parts store if needed. System capacity is 1.8lbs.

Any advise on troubleshooting further? Thanks in advance.
Mark

the ac system on that series of chev pickups were very well biult, did not leak much, small amount of added r134a will often be all that is needed, system should be about 30 psi running on 75 deg day , make sure fan clutch is working , i put a napa heavy duty fan clutch on a 6.0 2500hd , the ac was alway cold

 

[Walkers]

It is the seal on the compressor, plus, likely a hose or two. Just buy the compressor kit from RA, probably don’t need the condenser since the compressor hasn’t **** the bed, and add in any hoses that have oily spots at the junctions. You will likely be in it 3-4 hundred. You will need a vacuum pump, borrow, or use a sonic nozzle type from eBay cheap. You will need a set of gauges, HF $29 should work fine for one.
Or just add a can or two of refrigerant until the single gauge refrigerant tap kit is in the green.

 

[rust in the eye]

Lots of "it is this" comments when nobody has eyes on the truck.
Having said that after 20+ years I'd expect some refrigerant loss. Low charge after all these years could be a very small leak and a bit of gas will have it going again. I've had a bunch of old cars not worthy of a large investment that would require a bit of gas on an annual basis.
My personal experience with auto A/C is that leaks most often occur at seals on pipes or fittings and condensors which live in a vulnerable spot.
Good luck

 

[Raisedonadeere]

I have a 2003 dodge diesel, that the ac has always worked but around 2016 it started icing up (low refrigerant), So in a hurry one day I added about half a can of 134a, with no gages, expecting to have to add some from time to time, but it turned in to a every 2 years kind of thing. But this has to be a one-way street, leaks don't fix themselves, so I researched parts for a rebuild so I would be ready when the thing finally needed to be opened up. But this year it is working perfect after last recharge 3 years ago or was it 4. The parts house I was going to work with is out of business. But when it does **** out, I will be doing the rebuild of replacing seals, rubber parts and hopefully no evaporator coils under dash. That could be the end for me.

I have never heard of a leak slowing down. That is why I posted this. Now you have, a "believe it or not" thing to deal with LOL

 

[TractorJeff]

I read most posts.
Got confused when everyone said to fill by weight. They sell cans of refrigerant everywhere with a hose to "DIY" refill your car/truck. How do you know its "Full, not over Full"? Because you may not know how "Low" it is initially??

 

[bwringer]

Once in a while you get lucky and a can o' gas once a year or so does the trick and lets you limp along for a while.

Still, while you wait, save up your spare pfennigs and kopeks.

If it gets worse than a can every year or two, have a good shop with the correct machines do the work correctly, which will mean replacement of damn near everything. It'll be worth every penny, and within two of the truck payments you continue to not have to make, you'll be money way ahead again. After watching a guy just casually vent the whole system to the atmosphere with a Harbor Freight gauge set and vacuum pump (oh, and it still didn't work after he was done "fixing" it), I'm really super-duper not a fan of DIY A/C work. Have it done right with a recovery machine, sooner rather than later. None of us need to breathe that ****.

Another issue is that it can be damn difficult to find cans of plain R134A that do not come with "leak sealer" and/or other unknown potions and elixirs or dyes. You really have to read the fine print on the cans because they just love to sneak extra shite in there. Never, never, never never NEVER use this ****. The leak sealers are a one-way ticket to nonfunctionality and non-repairability. They're outright fraud, preying on the sweaty and desperate, and the parts stores should be ashamed for peddling that stuff.

Honestly, leak sealing potions of most sorts are outright frauds, and I often wonder why they're still on the shelf.

 

[Citation]

I would charge it with some uv due and run it again. See where it leaks. I believe that model has issues with evaporators and they are evil to change. At least with the dye you can be sure.

 

[Wrench97]

I have a 2003 dodge diesel, that the ac has always worked but around 2016 it started icing up (low refrigerant), So in a hurry one day I added about half a can of 134a, with no gages, expecting to have to add some from time to time, but it turned in to a every 2 years kind of thing. But this has to be a one-way street, leaks don't fix themselves, so I researched parts for a rebuild so I would be ready when the thing finally needed to be opened up. But this year it is working perfect after last recharge 3 years ago or was it 4. The parts house I was going to work with is out of business. But when it does **** out, I will be doing the rebuild of replacing seals, rubber parts and hopefully no evaporator coils under dash. That could be the end for me.

I have never heard of a leak slowing down. That is why I posted this. Now you have, a "believe it or not" thing to deal with LOL

Schrader valves do that you adjust it every time you add gas to it

 

[Wrench97]

I read most posts.
Got confused when everyone said to fill by weight. They sell cans of refrigerant everywhere with a hose to "DIY" refill your car/truck. How do you know its "Full, not over Full"? Because you may not know how "Low" it is initially??

The only way to fill by weight is if first evacuate the system so you know there is nothing in it.
You can fill by pressure but that takes some experience to know what pressures you should be seeing according to the temp and humidity in the shop/driveway/parking lot you're in.
The vast majority of systems if you 35 to 42 on the low side it should work there are of course some outliers I use to do a lot of old White trucks with RedDot add on units running R12 that loved to have the low side around 30 and when switched over to R134a they ran 15 on the low side and never had issues get them up to 30-35psi and the high side would spike to over 300psi.

 

[Raisedonadeere]

Schrader valves do that you adjust it every time you add gas to it

Good point, - - somewhere along the line I started making sure the cap is a good seal, using ones with an o-ring. Pretty sure no leak there so maybe that is why it is now holding. But a 21 years old system with over 200K miles is going to leak soon.

 

[DGersic]

I read most posts.
Got confused when everyone said to fill by weight. They sell cans of refrigerant everywhere with a hose to "DIY" refill your car/truck. How do you know its "Full, not over Full"? Because you may not know how "Low" it is initially??

That’s exactly the problem with the DIY can + hose setups. You don’t know. But it’s not all bad, if you can check the high side pressure, and it’s about correct, you’re probably close enough.

Dad used to teach this stuff, so I got lectured on it a few times.

The system is specified by how much refrigerant it needs to be full, from empty (vacuum). This is by weight. So the only “correct” way is to vac the system down, attach a gauge set and a tank of refrigerant to it, weigh the tank, and use the gauge set and scale to put the specified weight of stuff in. Then you check the high and low side pressures, and verify the temperature drop across the evaporator to confirm that the system is within specs and working correctly.

You’re not suppose to “top off” a partially full system. You’re supposed to recover what’s in it. You use a “recovery machine“ (fancy name for a pump). You connect it to the system, and to a recovery / disposal tank. Weigh the recovery tank, empty the system in to it, then weigh it again to see how much, by weight, you recovered. In theory, with a clean tank, you could put what you took out back in, and then you’d know, by weight, how much to add. I’ve never done that.

When my Dakota leaked, I got the environmental lecture on how I needed to properly recover the system before working on it. It took some arguing to get him to realize that a system that has leaked down to zero pressure hasn’t got anything in it to recover, so recovery isn’t needed.

When I was working on my Chevy street rod, I got the lecture on filling by weight. It took a while and some more arguing to establish that fill by weight only works if the manufacturer has and publishes a weight specification. As a custom system, all they could actually tell me is that most of the time, a full charge is around 10 to 20 ounces, but it depends on the installed length of the hoses.

Gemerally, I think the top off cans are, at best, a bandaid solution. If your system is leaking, you need to find and fix the leak. But, that’s expensive, and cans of R134a are relatively cheap.

 

[DGersic]

I have a 2003 dodge diesel, that the ac has always worked but around 2016 it started icing up (low refrigerant), So in a hurry one day I added about half a can of 134a, with no gages, expecting to have to add some from time to time, but it turned in to a every 2 years kind of thing. But this has to be a one-way street, leaks don't fix themselves, so I researched parts for a rebuild so I would be ready when the thing finally needed to be opened up. But this year it is working perfect after last recharge 3 years ago or was it 4. The parts house I was going to work with is out of business. But when it does **** out, I will be doing the rebuild of replacing seals, rubber parts and hopefully no evaporator coils under dash. That could be the end for me.

I have never heard of a leak slowing down. That is why I posted this. Now you have, a "believe it or not" thing to deal with LOL

If your 03 is like my 01 Dakota, taking the dash out to get at the evaporator isn’t especially hard, but it does take the better part of a day to get it out and back in. Having a second person to help take the dash out of the truck is helpful, but I’ve done it by myself.

The FSM for mine has a set of steps to remove it that are in the wrong order. I have a corrected set of steps for it that may help you. PM if you want a copy.

My 01 leaked at the evaporator, then at the schraeder valves. The valve on mine is not replacable, and I decided not to fix it. I’d have to replace the entire hard line, again.