Trying to Recharge Air Conditioner on my father's 1999 Land Cruiser

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I've successfully performed this service before on my own vehicle, but I'm out of ideas on what's wrong here.

Engine running and fan set to low with A/C light on.
Opened only Low Side valve to allow R134a into system but the compressor didn't engage. Jumped compressor clutch at under-hood relay box, and clutch engaged but system doesn't seem to fill.
Low side pressure climbs but high side pressure stays below zero.

[Context]
22 year old vehicle; system was already empty of R134a.
Replaced valve cores on both Low and High side ports.
System holds vacuum.

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flintknapper

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Can we get a little more info, it will help to determine the best way to proceed.

First, let's not run the compressor without sufficient refrigerant charge to carry the lubricating oil through the system. There 'should' be some amount of oil in the compressor....but I'd like a little more history before moving forward.

1. When was the last time the system was operating correctly?
2. The Schrader valve core stems were replaced *good move* presumably because they were leaking or just a precautionary measure?
3. Was the system completely empty/discharged BEFORE you changed out the cores?
4. Is the compressor on it now....the original?
5. The system under vacuum is holding at least 28Hg for 30 minutes or more now?


As concerns your gauge readings.....the zero reading on the high side is likely a crushed o-ring seal on one or both of the connections on the hose, so check that. It is easy to over-tighten and distort them or they simply wear out and need replacement, this is especially true on inexpensive gauge sets or 'rental' units.

The 'high' reading on the low side might only be the result of high ambient temperature and a fully open low side valve. Could be other things as well.

Compressor not engaging without being 'jumped' is normal until there is a enough refrigerant in the system to satisfy the Binary Switch *pressure switch* which will not allow the clutch to engage until you have approximately 25 psi on the systems low side.

When recharging a system from full evacuation....the above is why I don't like to make the initial charge through the low side. I prefer to charge the first 12 ozs or so as a liquid...into vacuum, via the high side *ENGINE OFF*, then finish the charge into the low side as a gas *compressor running, high side shut off*.
 
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1. Last known to be operating just over 2 years ago.

2. Replacing valve cores was a precautionary.

3. Yes, it was essentially empty. There was a tiny bit (~1 second puff) of pressurized gas that could be heard escaping when I opened the system.

4. Yes, original compressor.

5. Yes. I let it hold vacuum for 45 minutes and gauge levels remained static.
 

flintknapper

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1. Last known to be operating just over 2 years ago.

2. Replacing valve cores was a precautionary.

3. Yes, it was essentially empty. There was a tiny bit (~1 second puff) of pressurized gas that could be heard escaping when I opened the system.

4. Yes, original compressor.

5. Yes. I let it hold vacuum for 45 minutes and gauge levels remained static.


Good thanks...that is helpful.

So.....you pumped the system down and it held vacuum. When you went to charge the system with refrigerant is there any chance that you lost vacuum hooking up the charging hose or manipulating valves? It is very important that we get the first 12 ozs or so into the system with NO air being introduced from not purging the lines or a leak you are unaware of with the manifold set.

I'm sorry if this sounds remedial and I don't wish to insult anyone. I just don't know how experienced a person is *or isn't* when doing A/C work, so please forgive me if some of my questions seem to have obvious answers.

Also, you will need to look at the hose on the high side and see that the seals are not dislodged or crushed looking. About the only way to have a Zero reading there *common reason anyway* is to have a faulty gauge or blockage in the line.
 
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Bless you kind sir.

I followed your advice and it's working now.

I returned the rental gauge and bought my own. I also filled the high side first with the engine off.

This saved my father a bundle.
 

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