What am I missing with the A/C system? - 2006 Toyota Highlander

[Zack1978]

Hi everyone,
I need some guidance with the A/C system on our 2006 Toyota Highlander. The A/C is system is not operating at all now. In the past it had a very slow leak and a quick shot of R134 would have it running fine for a full summer, now that no longer works. I am at a loss to understand what is happening with the system now, specifically related to the pressure.
When you have a pressure gauge on the low side, the system registers full or perhaps even a touch over pressure; but only with the system off. As soon as you turn the system on, the compressor kicks on and the pressure immediately drops to zero on the gauge. What would cause the system to do that? It doesn't make much sense to me, but I have VERY limited knowledge about this system of the car.
We are the original owners of the Highlander and it has high mileage, the A/C system is original. Any ideas?


Thank you

 

[Chris142]

It's all leaked out is my educated guess without a high side reading which is much more important than a low side reading.

Ignore the pressure when the compressor is off. It's meaningless at this point.

 

[clinebarger]

Low refrigerant would be my guess.

 

[JHZR2]

You had a leak. You didn’t repair it, just refilled it, which is technically against the law. The leak got bigger. I’m guessing you didn’t run your ac, so seals didn’t stay lubricated, and oil coating the system. Then you tried to turn it on and nothing..

 

[spasm3]

Low on refrigerant , unless you are careful , each charge with the hose gives the system a whiff of moist air contamination.

System needs to be evacuated, put on a vacuum to see if it holds, if not , leaks need to be fixed, perhaps a new receiver/dryer ,and then recharged by weight.

 

[CleanSump]

When off the pressure goes high on the low side and low on the high side - it equalizes throughout the system.
When the pump is on, it is sucking down the low side (pressure drops) and pumping up the high side (pressure rises).
You have a leak that is getting bigger. Have it fixed by a shop that specializes in AC. The leak needs to be located, system evacuated, seals replaced, should replace the receiver-dryer, pull a vacuum, then refill with correct amount of oil and refrigerant.

 

[KrisZ]

If it still registers pressure when off, then the system is not all empty and there is still refrigerant in there. You can still top it off and it should start working again.

 

[mrvmax]

You cannot just keep topping it off, eventually you will need to fix the leak. Add some dye, see where it is leaking, fix that, vacuum the system and recharge. Sometimes leaks are easy to fix (like the Schrader valves) and other times the entire dash needs to be removed.

 

[SC Maintenance]

I bought this freon leak detector on the advice here of others. It was the best $20 I have spent in a long time. https://www.amazon.com/dp/B0DSBJBNY5?th=1

I do however agree with the others that you can't just keep topping it off. I have fixed three systems in the last year with a few tools and lots of help from here. 2 of them were just an o-ring and turned out to be very easy once I knew a little bit on what to do.

I suggest reading this thread: https://bobistheoilguy.com/forums/t...oubleshooting-101-help-me-get-started.395707/

 

[zzyzzx]

I need some guidance with the A/C system on our 2006 Toyota Highlander.

How many miles are on the vehicle?

 

[Marcozi]

I'd take the car to a reputable automotive AC shop. Have the tech refill the system with refrigerant with UV dye. When the AC stops working take the car to the shop and have them find and fix the leak. Then have the shop replace the dryer (it's 20 year old and likely shot) and perform a refill procedure.

 

[D60]

Make sure the caps are on both valves. So many people discard these.

Next time listen carefully when you pull a cap. If you get a pfft that valve is probably leaking. Now, of course this may not be your only leak.