Need some advice from the AC experts

[Drcoffee]

My '99 T4r had lower pressures than it should have. So I topped it up with new freon and the vent air stopped being cold. Here is what happened.

Connected the manifold gauge set and started the engine. At idle the low was 15#, high was 150#. Increased rpm to 1500 and the low was 12# high 135#. The sight glass looked like it was foamy, not a clear fluid stream.
I added freon until the low was 35# and high 200#. Then the cool vent air went warm. So pressures were correct but the AC blows warm. Gave it time to normalize and the high side at idle went to 250# and low 45#. But still no cold air and no condesation on pipes. So I bled off the new freon back to 15# and 150#.

At this point I am baffled. I plan to evac and recharge but why would the vent temps rise when the pressures are textbook?

Thanks

 

[jhfleet]

Was the air purged from the manifold set before adding Freon? Really shouldn't make a lot of difference with typical length hoses, but that's the only thing I can think of. The pressures sound great for typical summer air temperatures.

 

[Drcoffee]

Now that I think of it, I purged the yellow hose but not the manifold. Would that be enough to stop the cooling of the system?

 

[jhfleet]

Now that I think of it, I purged the yellow hose but not the manifold. Would that be enough to stop the cooling of the system?

I dunno....It's very important on systems that don't hold much Freon such as refrigerators and so on. But, on a T4R it really shouldn't have a huge effect unless there was already air in the system. I'd probably evacuate it and recharge since 134 is cheap.

 

[stir_fry_boy]

^^Agree

 

[Buckaroo]

As opposed to R-12, difficult to charge R-134a accurately based on pressure or site glass and over/under charge will cause system performance issues. Need to charge based on weight of refrigerant added which means you need to recover and recharge total amount to make sure you get it right.

Buckaroo

 

[Drcoffee]

That's what I was thinking but I started to worry the expansion valve needed changing because the cooling never improved.

At this point would using the Arctic freeze stuff with sealant and oil included be a bad idea or would it be okay? 15 year old truck, I'm sure the seals are getting dry.

 

[jhfleet]

That's what I was thinking but I started to worry the expansion valve needed changing because the cooling never improved.

At this point would using the Arctic freeze stuff with sealant and oil included be a bad idea or would it be okay? 15 year old truck, I'm sure the seals are getting dry.

I've never used that particular product but it's probably okay. If there's no oily residue visible you probably don't need to add oil but the premix stuff likely won't hurt anything. And, like Buckaroo said, recharging by weight after evacuating the system is the best way to get the correct fill. BTW, if the evaporator is leaking and/or the expansion valve has crapped out it's not all that hard to fix. No need to pull the dash on Gen 3s to get to that stuff.

 

[Drcoffee]

Good to know. BTW it has 1oz of Ester oil and not PAG46. would that harm the system?

quick story: I just replaced the compressor, condensor and expansion valve on my daughters 2000 Rav4 last week. Had the whole thing out including the evaporator and lines to flush it all clean. There wasn't a drop of oil in the compressor which is why it seized. My guess is the condenser has a leak.

One day to pull it all out and the second to re-install, third day to vacuum and recharge. NOT FUN!

 

[jhfleet]

Good to know. BTW it has 1oz of Ester oil and not PAG46. would that harm the system?

quick story: I just replaced the compressor, condensor and expansion valve on my daughters 2000 Rav4 last week. Had the whole thing out including the evaporator and lines to flush it all clean. There wasn't a drop of oil in the compressor which is why it seized. My guess is the condenser has a leak.

One day to pull it all out and the second to re-install, third day to vacuum and recharge. NOT FUN!

You're getting above my pay grade! I think most systems with 134 use PAG oil of whatever viscosity and Ester is used mostly in R12 systems converted to 134. I have no idea of whether they mix.

 

[JRZEE2000TR4LTD]

You're getting above my pay grade! I think most systems with 134 use PAG oil of whatever viscosity and Ester is used mostly in R12 systems converted to 134. I have no idea of whether they mix.

Ester oil is the "universal" oil so it mixes ok with the PAG. R12 usually came with mineral oil and that is not friendly with the PAG.

OP, my opinion is it seems like you went from too little refrigerant to too much, just going by the pressures you stated. Low side should be between 25-35 psi and hi should be between 200 -225psi. These pressures would be on a normal day (ambient temp around 80 degrees)
As already stated, in 134A systems, there's not a lot of room for error. If you did have low refrigerant then you obviously have a leak, which would need to be fixed. I guess it would be worth it to evacuate and recharge with the correct amount for no other reason then to make sure everything is working right. Maybe you'll be able to make it through the summer if it's slow enough. Good luck!

 

[Buckaroo]

Would not use the r134-a that contains the sealant - bad stuff. Shops that do A/C right (and obey the law) will not touch your system if it is charged and contains sealant as it will gum up their $5,000 machine. Typical to test for sealant before hooking machine up and, if present, not go any further with recovering or charging. If you have leaks, better to locate and fix them.

Buckaroo

 

[BamaDrewski]

My '99 T4r had lower pressures than it should have. So I topped it up with new freon and the vent air stopped being cold. Here is what happened.

Connected the manifold gauge set and started the engine. At idle the low was 15#, high was 150#. Increased rpm to 1500 and the low was 12# high 135#. The sight glass looked like it was foamy, not a clear fluid stream.
I added freon until the low was 35# and high 200#. Then the cool vent air went warm. So pressures were correct but the AC blows warm. Gave it time to normalize and the high side at idle went to 250# and low 45#. But still no cold air and no condesation on pipes. So I bled off the new freon back to 15# and 150#.

At this point I am baffled. I plan to evac and recharge but why would the vent temps rise when the pressures are textbook?


Thanks

I did a 100% rebuild on my 2000 T4R's AC system last year.(http://www.toyota-4runner.org/3rd-g...-replacement-2000-toyota-4runner-limited.html) I replaced the expansion valve, evaporator core, compressor, condenser, drier, pressure switch, all new O-rings, etc. (Bought all Denso parts on Amazon [with the exception of O-rings & pressure switch] for a lot less money than a guy quoted just to replace the compressor with somecheap Chinese knock-off)

I flushed all the pipes out when I did the rebuild and made sure I had charged the compressor with PAG oil (green) before I put it together. They recommend putting a vaccuum on the system for at least 20 minutes before recharging.

I would recommend you find a shop and negotiate a price to pull the vacuum for 20 minutes and do a full recharge through a machine. My buddy had a SnapOn AC system that did everything with just the touch of a few buttons and programming the year/make/model on the system. The system has run like a TOP ever since and blows 38 degrees on the coldest setting in 105 (heat index) temps here in Alabama.

I will say this; when I took the entire AC system apart, the enclosure for the evaporator core was filthy. I actually washed it in the dishwasher and came out like new. Also, the condenser coil behind the grill was SHOT. After 15 years, everything just rusted through and fell apart. For less than $600, you can rebuild your entire system with great parts and get 10-15 more years out of your AC.

 

[Drcoffee]

Update: i had the opportunity to recharge the system today. All that I read on 134a the system needs to be refilled with a specific amount of fluid. In the case of the 4runner, its 22.9 oz. +- 1.7 oz. so I pulled vacuum for an hour and let sit for 15 minutes. No leaks. I used one 12oz can of straight 134a and one can of Arctic Freeze 11oz 134a plus 1oz oil. Total refrigerant of 23 oz.

Ambient temp 70*
The pressures were 35-40 low, 250-300 high.
The high side seems high but I plan to let all the new liquid stabilize and recheck in a few days. It blows cold so at this point it looks fine. The only unknown is oil quantity but pulling the compressor looks like a pain in the butt. I would rather have a little extra oil than not enough. I will just roll the dice for now.

 

[4Reak Show]

Never EVER use a leak stopper in A/C systems! ...EVER

Leak stoppers are easily the worst idea any human has ever created for an a/c. 2 huge reasons: 1) it locks onto anything that has oxygen (in theory, a leak) and solidifies. HARD. Rock hard. Having an air pocket in the system could be catastrophic. 2) if you install it incorrectly and breathe in the leak stopper, it has been known to enter one's lungs and potentially become fatal.

Those are worst case scenarios but it has happened. Take it from a 9 year ASE master technician and avid yota lover. Never use over the counter leak stopper. Just don't. If you don't have the machine, buck up and take it to a pro who has the right stuff.

The aforementioned snap-on machine is in the neighborhood of $5000 for a reason. They are the right way to do it.

That being said, your original issue about having the pressures correct and ideal yet poor performance, doesn't take into account a simple part of physics: pressure does not equate volume. Look at a tiny camper propane tank. It has a specific psi, but the VOLUME of propane (actual physical quantity of the material) is much less than a standard 5 gal tank of roughly the same pressure.
The only way to be certain of a properly filled system is with a full recovery, vacuum, and recharge with a calibrated machine. I don't even trust the over the counter preweighted cans.
If I were you, I would take that leak stopper out immediately, and also tell any shop who might work on it that that stuff is in there, or it could ruin their equipment.
Sorry for the length but you said you wanted an experts opinion...you got it. Good luck sir

 

[Drcoffee]

I appreciate your candor and honesty. I agree with you 98%. Take a step back though. In an ideal world, everyone would gut their system and rebuild it so that it runs like new. In the real world though, we have 16 year old vehicles that are wearing out and use decades old technology when they were built. Here is my thought on the topic. My refrigerant levels were low when I first checked it. So there must be a small leak sonewhere. I bought the truck with 155,000 already on it. So who knows what has already been done to it up to then. I can either spend $30 and recharge the system and see how it responds or spend at a minimum $400 for new compressor, condensor, exp valve, evap and DIY it after a full flush or spend thousands to hire it out. In my mind, if my $30 evac and recharge works, i am way ahead in time and treasure. If it fails, I needed to rebuild it anyway. As I mentioned, I rebuilt my Rav4 ac system a month ago. Its not a bad repair but not a quick one either. So I chose a product with minimal sealer but has a booster and oil incorporated into it. If I had to guess, I believe the expansion valve needs to be changed based on the pressures I see. So if I go that route and open the system I will have to do a full flush. On a side note, i am way over due for the timing belt water pump service. While I am doing that (requires the compressor to come off) I may do the whole ac flush and repair then. I just need to buy some time. If it holds, all the better.