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Discussion Starter #1
Last summer the AC on our 99 was weakening. Also, the blend actuator was making a clicking noise almost constantly. Following a YouTube tutorial I cleaned it and regreased it. That resolved the clicking. Before a long road trip to TX from IL I added refrigerant but possibly overcharged the system. During the trip it would cool and then switch off and blow very hot. Then it would kick back on and blow cold again. We dealt with this during part of the summer. In case it maybe had something to do with the blend actuator, I replaced that. It didn't seem to help but we were soon out of the summer months. During the winter months it has also been acting strangely. At the lower temperature ranges on the dial, it blows the hottest air. Moving up to the higher temperature ranges it is cooler but still hot.

Currently, the system will not blow cold at all. The refrigerant appears to be low. It registers about 25PSI on a refill gauge at the low pressure port. Also, the compressor will not engage at all.

Is there a comprehensive troubleshooting thread available here in the forum somewhere?

Is there any advice on where to start? We're taking our annual TX trip in a few weeks.
 

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There have been several recent troubleshooting threads in the 3rd Gen section. Some common points that I have gleaned:
1)
I added refrigerant but possibly overcharged the system
Overcharging can damage the compressor.
2) Using cans that have 'leak guard' or sealant can harm the compressor.
3) The only sure way to know that you have the proper amount of refrigerant is to evacuate the system and weigh the refrigerant to be added.
4) The days for us average 'shade tree mechanics' to fix our A/C with manifold gauges and cans of refrigerant are gone.
 
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25 psi with the compressor not running is practically empty of refrigerant.
 

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Discussion Starter #4
I tried adding refrigerant but it wouldn't go in. Doesn't the compressor need to engage to help with that?
 

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Yes, the compressor needs to run but won't with so little refrigerant. With that little refrigerant in the system if you engergize the compressor that will drop to zero, or less, and the refrigerant would go in. However, you can damage the compressor by engaging it with so little refrigerant. You'd be best off to take this to someone who knows what they're doing. It likely has a leak and that's why it's so low.
 
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I would invest in a set of ac gauges to troubleshoot your ac system properly. You need to get the high and low pressure lines values to understand what is going on in the system. Those gauge attached on the add a refrigerant can kit may not be as accurate as you want it to be. Go spray some soapy water in your low and high ac ports to check for leaks. When I had a leak on the shrader valve low port many years back, my ac gauges reading was like 10 psi-low. I was able to fix the leak and add 3 cans of refrigerant 12 oz ea. without needing to evac the system. Since then, the ac has been blowing 40 deg in our hot Vegas summer temp of 105-115 deg lasting at least 3 months. That was about 5 years ago I think. I have a thermometer permanently inserted in the front center vent ever since that repair. So I can see how the ac is performing all the time. Good luck.
 

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I would invest in a set of ac gauges to troubleshoot your ac system properly. You need to get the high and low pressure lines values to understand what is going on in the system. Those gauge attached on the add a refrigerant can kit may not be as accurate as you want it to be. Go spray some soapy water in your low and high ac ports to check for leaks. When I had a leak on the shrader valve low port many years back, my ac gauges reading was like 10 psi-low. I was able to fix the leak and add 3 cans of refrigerant 12 oz ea. without needing to evac the system. Since then, the ac has been blowing 40 deg in our hot Vegas summer temp of 105-115 deg lasting at least 3 months. That was about 5 years ago I think. I have a thermometer permanently inserted in the front center vent ever since that repair. So I can see how the ac is performing all the time. Good luck.
Added 3 cans? The system only holds 30-31.7 oz max so you were over charged, and if there was any charge left in it prior to adding, you were WAY overcharged. On the vans without rear AC the charge is 22.9 oz which is less than two cans.
 

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Added 3 cans? The system only holds 30-31.7 oz max so you were over charged, and if there was any charge left in it prior to adding, you were WAY overcharged. On the vans without rear AC the charge is 22.9 oz which is less than two cans.
We had this discussion before, but to answer again, I am certain from my experience that in a given 12 oz can of r134a refrigerant there is absolutely no way to fully empty the 12 oz content inside any ac system. There will always be a) a little left inside the can-I always hear a little hiss when I remove the pin from the can ; b) There will always be some left inside the hose lines of the gauges; c) Switching between cans will also cause a little to escape. d) Removing the sharader valve connection from the ports always causes a hiss meaning a little escapes from the system again. So yeah, I know that I did not overcharge my system shown from the reading I got from the gauges. I was very careful and vigilant as I add each can. Now, if I said that I put 4 12 oz can in there...that is a totally different story. For sure that will be an overcharging even with the above mentioned factors. One should see it on the gauge reading as well. I seem to remember you being overly cautious about this because you had a bad experience of overcharging yours or something to that effect. Costing you more in the end. My experience is different. So far, since that repair, its still running great and blowing 40 deg just yesterday when we had a 106 deg temp day. Cheers.
 

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I don't remember having the discussion before but, I can concede maybe we did.

As long as there is no liquid left, whatever is left in the can is negligible in weight as it's just a small amount of vapor that's left. I have weighed them before and after and you easily get 11.9 - 12.1 oz into the system. I have weighed the cans before and after and the cans I use are quite accurate in the 12oz listed on the can. I've always had 12.0 - 12.2 oz in every can and easily get virtually that same weight into the system. Yes, some will be left in the hoses but if you properly remove your hoses you will be left with only a very negligible amount of vapor in your gauges. If you don't properly disconnect you will leave an ounce or so of liquid in the red high side hose. Here is how to properly remove hoses: 1) Ensure both valves on the manifold gauge are closed. 2) Close the high side service coupler and remove it from the system. 3) Open the high side valve on the manifold gauge to allow the liquid contents of the high side hose to enter the manifold. 4) Very slowly, while the AC is running, slightly crack open the low side valve on the manifold gauges to allow the liquid into the low side, and into the system. Its important to open this only slightly to vaporize the liquid so that pure liquid doesn't go into the low side and slug the compressor. 5) Once the high side pressure gauge reads the same as the low side gauge, close the low side service coupler and remove from the system. If you do this there will be onlly a small amount of vapor left in the gauges when you are done. It's nearly too small an amount to even weigh, just like an empty can.

Purging air from your yellow charge line between can changes, again, lets out only a very small amount of vapor so negligible weight. You shouldn't be charging liquid (can upside down) anyway.

I guarantee if you put three cans into a system that holds about 30oz, and especially if already had ANY refrigerant left in it, you overcharged the system. I've said it many times...it is impossible to tell the state of charge by gauge pressures alone. It may get cold but it probably doesn't work as well as it could if it was properly charged, and you risk damage to the compressor and expansion valves.
 

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Discussion Starter #10
Well, all of that back and forth is very educational. Today I got the gauges through the Autozone Loan-A-Tool and, yep, pretty empty. Both high and low side registered only about 15 psi. I also noticed when I removed the gauges that the low side Schrader valve was pretty sticky. So, I also checked out the vacuum pump, dye kit, and got the supplies to replace both Schrader valves. Tomorrow I plan to vacuum it and see if it holds the vacuum. Then, hopefully, fill it (following a very detailed YouTube video) and see what happens.
 

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You can have a leak anywhere, however, in my experience, most leaks are either in the condenser or the compressor. A good visual inspection can sometimes find these leaks ahead of time. Take a good look at the condenser for any oil staining, usually at the sides where the tubes meet the cylinders. When there is a leak it will leak oil there and have a spot that looks wet when the rest of the condenser looks dry. See the pic below for an example. It's kind of an extreme example as you can see the oil itself. Sometimes you'll just see the dark staining. Also, look at the compressor, usually on the bottom where the clutch mounts to the compressor. Often you'll see it wet with oil from a compressor shaft seal and/or where the halves of the compressor bolt together. These are just two places that are common and sometimes able to easily see with the naked eye. Of course, as you found, the service port valves can leak, as well.

For charging the AC, always keep in mind how you might be letting air into the system. Bleed all your hoses and do all you can to avoid any air. Follow the instructions on how to switch cans and how to properly remove your gauges when you're done so you don't take liquid refrigerant with you when you're done. AC is not difficult but it can be complicated and things can snowball on you.

Good luck!


155555
 

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You will need a special tool to avoid using the vacuum pump if you still have pressure in the system. But if you want to let the remaining refrigerant out and use a vacuum pump then that surely would work also. I opted not to use a vacuum pump in my situation.--more environmentally friendly. Its a good sign you have a low and low reading. That points you to a low refrigerant only and adding more should make it cold again. Spraying soapy water on the ports will easily show if you have a leak there or not. If it keeps bubbling then you have one.
 

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To check for leaks you need pressure in the system hence more refrigerant. Before emptying your system, add more first and look for leak that way. Easier. If you keep pressure in your system you don't have to use a vacuum pump if your leak is from the ports. If its from any other place then a vacuum pump is a must.
 

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You will need a special tool to avoid using the vacuum pump if you still have pressure in the system. But if you want to let the remaining refrigerant out and use a vacuum pump then that surely would work also. I opted not to use a vacuum pump in my situation.--more environmentally friendly. Its a good sign you have a low and low reading. That points you to a low refrigerant only and adding more should make it cold again. Spraying soapy water on the ports will easily show if you have a leak there or not. If it keeps bubbling then you have one.
NOOOO......don't do that. 15psi left? That's almost nothing--it's practically empty now and likely will be empty if you wait another few days anyway. Connect your gauges, open the low pressure valve on the manifold and let that last little bit out the charge hose. Replace both shraeder valves with new ones. Lube them up with a little PAG oil. After that, vacuum it down for 10 minutes and then turn the vacuum pump off and close the manifold valves for 10 minutes. Let it sit for a minimum of 10 minutes and make sure the vacuum gauge needle doesn't move over that time. That will allow you to see if there are any leaks under vacuum. If it passes that then vacuum it down for another 30-45 mins. Then weigh in your refrigerant. It will take you a few extra minutes but you ensure no moisture or air in the system that way, and you know your charge level is 100% correct. You also check for leaks.

All that said, just because a system doesn't leak under vacuum doesn't mean it won't leak under pressure but at least you know you don't have any large leaks.

If you let the vacuum sit for 10 minutes and the system loses vacuum indicating a leak, then you're going to want to add some dye and maybe 1 can of refrigerant, run the system, and look for your leak. Finding hidden leaks can sometimes be a challenge, though.
 

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If you want to start by adding dye and one can of refrigerant I don't have an issue with that. With that 15psi in there you could probably add two full cans of refrigerant without overcharging and see how it goes. However, if you need to affect a repair, it's not good to just let out that much refrigerant.
 

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Discussion Starter #16
By the time I got the low pressure port valve to close it was down to about 8 psi (according to another reading. So, yes, I loosed the Schrader valve and let the last bit out so that I could do the vacuum test. I will also look for staining around the system and work to replace any seals now that the system is completely empty already.

Thanks to both. Keep the thoughts coming.
 

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It's possible your leak has been the schrader valve all along. What often happens is they will be fine until you put a hose on them and then they won't seal afterward but it might have been leaking prior. If you don't see any signs of oil leakage at the compressor and the condenser, I'd probably take the risk of just replacing both of the schraders and then evacuating and charging it. Get some dye to put in it so you can look for leaks in a couple weeks. You'll need some glasses and a UV light but at least the dye will already be in it.

You don't want to keep the system open because the receiver/dryer in the condenser will absorb moisture. It really should be replaced when you open a system. If it's only open for a few minutes you can get away without changing it but much longer than that and it really should be replaced.

One more tip...When you put your hoses on, and open the valve, don't crank down on the valve. Just open it enough to vacuum and charge. If you crank it all the way until the valve won't turn anymore sometimes you can damage the schrader valves. If you do hit bottom when opening it don't crank on it hard, just back it off a little and leave it nearly full open.
 

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NOOOO......don't do that. 15psi left? That's almost nothing--it's practically empty now and likely will be empty if you wait another few days anyway. Connect your gauges, open the low pressure valve on the manifold and let that last little bit out the charge hose. Replace both shraeder valves with new ones. Lube them up with a little PAG oil. After that, vacuum it down for 10 minutes and then turn the vacuum pump off and close the manifold valves for 10 minutes. Let it sit for a minimum of 10 minutes and make sure the vacuum gauge needle doesn't move over that time. That will allow you to see if there are any leaks under vacuum. If it passes that then vacuum it down for another 30-45 mins. Then weigh in your refrigerant. It will take you a few extra minutes but you ensure no moisture or air in the system that way, and you know your charge level is 100% correct. You also check for leaks.

All that said, just because a system doesn't leak under vacuum doesn't mean it won't leak under pressure but at least you know you don't have any large leaks.

If you let the vacuum sit for 10 minutes and the system loses vacuum indicating a leak, then you're going to want to add some dye and maybe 1 can of refrigerant, run the system, and look for your leak. Finding hidden leaks can sometimes be a challenge, though.
I don't know what you are objecting about in what I said? All I'm saying is find the leak first by adding more refrigerant now while you still have pressure in the system and before going through the whole evac process. And the option of using this tool https://www.amazon.com/Mastercool-58531-Black-Standard-Remover/dp/B0015KH93K?tag=vs-auto-convert-amazon-20 if your leak is only from the ports then you can avoid needing to use the vacuum pump entirely. But if your leak is from any other component then the vacuum pump will be a necessary tool. Saves money and time.
Anyway, now that he removed all the pressure he needs to vacuum pump before recharging and find the leak. Evac the system again, fix the leak, vacuum pump then recharge again.
 

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Putting some in to find a leak is fine, as long as you know you're not close to overcharging. You just can't charge it and think you're done. You may get lucky and charge it close but most of the time you'll be under or overcharged.

As for the tool, I have the master set. They do not always work. I even got one stuck one time where the valve wouldn't come out and I couldn't get it back in. I had to use my AC machine to evacuate from just one side in order to get the tool off. It's a great t tool but there are numerous sizes and it's not a 100% effective tool.
 

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I found the harbor freight freon detector tool to be quite useful in finding leaks. But it does take some experience to know how to interpret the readings.
In my case, the evaporator and rear lines were leaking. In NJ where they use salt on the roads I found corrosion where salty water got in between the aluminum lines and foam insulation. The leak detector found the freon coming out at the end of the foam insulation. The aluminum lines had corroded.
Found freon detected at the water drain tube from the evaporator.
I replaced the condenser as a precaution since all the fins were blown away from road debris. Then I put a trans cooler down low where all the road debris enters at the bottom section of the bumper. So the trans cooler takes the hit. It's easier to replace than the condenser or radiator.
 
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