coryc85

All - over the years I have converted my AC over to r134, with pretty dismal results. The last time I thought I really did my best job ever, changed all o-rings, flushed compressor, vac'd system down, new drier, and charged up. Looking back thru my posts I think the system got down somewhere in the low 60 vent temps. And it actually felt ok at the time, but then later with a brutally hot summer, 60 deg vent temps don't do much except blow some of the sweat off your hands. So I'm kindof on a quest to really give this AC my best effort yet before next summer gets here.

1) *Rebuild or replace the compressor (haven't decided which)
2) New drier
3) *New expansion valve
4) *Remove and flush evaporator fins and internally
5) Replace all o-rings and flush all the lines

Here's where it gets questionable
6) Convert to parallel flow condenser??

For all of you who have r134 converted 4Runner ACs(sorry truck owners, I'm assuming the extra volume of air makes a big difference)...are you using all stock parts, and is your AC cold? Cold as in 40-50deg vent temps?

With the parallel condenser, I'd likely have to make some sort of mounting brackets, then probably have new AC lines made, so there is some work and $$ if I go that route.

Can I get to 50 deg or less vent temps with the stock condenser on a converted system? And BTW, I live in South Florida where mid 90s and nearly 100% humidity are just normal summer days.

Thanks for any inputs.

scope103

I got 46° vent on a 75° day. While I'm not blessed with your delightful tropical weather, it's been plenty cold for me. https://www.yotatech.com/forums/f116...-r134a-284801/

So my first thought is that a successful conversion is possible if done correctly. Did you use pressure and temperature gauges to charge it? I used these instructions and this checklist when charging.

wyoming9

iTrader: (1)

I hope you at least cleaned the Evap coil .

They get full of dirt after all these years which can really limit how cold things get .

Now going back some years in school for HVAC we were taught a 40 degree vent temperature difference was about normal .

Have things advanced more allowing for colder temps??

Then 4Runners are harder to heat and cool .

coryc85

Scope - wow, great thread. I did use gauges and I tried to use the info from the temp/pressure charts. My readings were something like 60 on low side and 175 on hi side, which to me looks like low side too high and high side too low. I kindof inferred that meant I was low, but I tried adding some r134 and did not seem to change anything, it did take some b/c the can got cool. I don't think I overfilled it, because remembering back to when I did the fill it only took a little over 1 can. Some have suggested perhaps my expansion valve is bad, I figured that is a cheap part so I will likely change it on my next go round.

Well, Evaporator was removed once 4 or 5 years ago and we did clean it very well. Since then I have twice now tried flushing it while in the vehicle but probably it needs more pressure than I can squirt up in there.

Have things advanced? I really don't know. I do know that converting to r134, this system will never be as good as r12, so I want to set my expectations. I wonder if 40 deg difference is normal for an r12 system, I imagine r134 couldn't match that, so maybe 30 deg difference?

I am basically at or very near 30 deg difference now, and I don't like it. You guys are certainly making me think....

Problem 1:
I don't think my pressures are where they should be, maybe that's a problem with the expansion valve or maybe my compressor is bad or weak, or maybe I overfilled/underfilled.

Problem 2:
Perhaps my evaporator is very dirty, I can't really see it, certainly could be dirty and clogged.

scope103

You can't use gauges alone; you need gauges plus temperatures. I suppose someone who does this ALL THE TIME knows their ambients so well that they can guess-tify it from pressures alone, but that wasn't me.

My evaporator wasn't "too bad" after 20 years, but I have a garage. If you're parking under the trees they can fill up pretty quick. Your call; removing an evaporator is long, fiddly job. If you do take it out, replace the expansion valve, and flush the core. You can't flush an evaporator with the expansion valve in place.

R12 "better" than R134a? Yeah, yeah, maybe. Just suck it up; no auto manufacturer has used R12 in over 20 years, and you don't see people dying from heat exhaustion.

Don't forget, clothes make the man! One hot summer, one of my partners came into the office with this incredibly loud pink suit. I asked him about, and he said "Oh, that. I asked my wife to go to Cox's and get me a seersucker suit. But she got confused, and went to Sears."

coryc85

Scope - your input is much appreciated, your thread is fantastic. I did not know that Autozone had that loaner flush tool, I will be checking on that for sure.

You are starting to give me hope that with a new compressor, new expansion, and thoroughly flushed evaporator, I might be happy. As it is right now, I can't drive this 4Runner on hot day down here. We'll see, I'd still like some more of a sample size to see how many people are comfortable in their 4Runner on a really hot day.

87runner_

iTrader: (1)

Hi Cory,
With the low side high and the hi side low...this can mean a weak compressor, assuming your expansion valve isn't stuck open.

One way you can check is to fully stabilize the entire system for testing.
This takes about 15 mins or so, sometimes longer.
Here's how I do it:
- Make sure engine is at FULL operating temp & gauges hooked up
- Open all vents
- Turn blower on Hi/Max
- Stick an accurate thermometer in center vents
- Fast idle engine (I stick a small flathead into the throttle to ~1800-2000 RPM)
- Using a garden hose, hose down the entire front of the condenser well for about a full minute or so. The idea is to try to get the system to cycle (compressor to temporarily shut off automatically) because you're liquefying all the refrigerant. Best to do it while it's hottest outside.

Note: Make sure you're parked on an incline so the water runs away from you...unless you want to get soaked.

If you can't get it to cycle, the system isn't working efficiently enough.
This process will often "unstick" a sticky expansion valve...and can reveal if it is sticking.

Regardless of whether it cycles, monitor the coldest temperature you can get. Also, these are the lowest pressures you'll see. Low side should usually be below 30psi (maybe even below 20psi). High side will be around 100psi-ish, give or take.
If it does start to cycle, turn the water off and note your vent temperature. This is about as cold as you're going to get.

Then, wait until the clutch fan begins to re-engage again. Both pressures will be rising again. You should see both pressures drop when the fan engages and begins pulling air again. If it's not real hot out the a/c system will generally continue to cycle periodically, assuming the system is working properly. Typically you'll see the vent temps drop a few more degrees at this point and you should be able to see the gauges (especially the hi side) drift a bit back and forth as the expansion valve opens and closes.

If your pressures are as you stated above (low is too high & hi is too low) and nothing changes after doing this hose process, I'm gonna say you have a weak compressor.

One thing to keep in mind...on these trucks the gauges are read directly off the compressor (I totally HATE this!). This is not a very accurate reading because you're reading values AT the compressor. Ideally you want just before & after the evaporator...but that's another discussion.

So...this means that your low pressures will (should) be LOWER than normal, and your hi pressures will be a bit HIGHER than normal.
Also, as a rule of thumb, the high side pressures should be about "double the ambient temperature" + or - about 20%...ish.
Thus: If it's 100 degrees outside, 250psi is pushing it. With 134a you might be closer to 300psi.

If your compressor is weak, I'd personally be reluctant to run the A/C at all...you do NOT want that to go "black death" on you. That will be a bad day.

==========
As another note...I swapped my factory 'tube & fin' for a parallel flow condenser (tho I kept it R-12). Blows ice cubes! I've gotten my A/C system to cycle (cycles at 33*F) at a red light when it was 110*F out.
I highly recommend this modification. The tube & fin style is awful!!

I believe the one I purchased was a universal 12"h x 24"w. But had to take a large hammer to the lower subframe to make it fit, and I had to cut a piece of the aluminum bracketry from the condenser bottom and had a couple of custom fittings made. Overall it wasn't really that big of a deal to have done. Just took a little patience.


One other thing...I don't care what anybody says...use the native oils. Always!
For R-12 always use mineral oil
For R134a always use PAG oil.
I'm no fan of ester oil.
Your compressor will reward you for it!



Hope this helps!
-Mike

87runner_

iTrader: (1)

Also...here's a GREAT way to clean your evaporator core (once you pull it out):
(The evap cores are pretty easy to take out of these trucks once you undo the hose connections at the firewall...remove the glovebox and a bunch of 10mm screws in the dash...voila!)

- 5 gallon paint bucket
- Bottle of Palmolive dish soap
- Water
- Compressed air

1. Remove the expansion valve.
2. Place the bare core into the bucket, fill it will water to cover the whole core (doesn't matter if water gets into the tubes).
3. Put a *LOT* of soap into the bucket. (don't use cheap dish soap)
4. "Plunge" the evap core in the water to agitate it and mix it up well.
5. Let it soak for TWO DAYS...agitating it occasionally.

After the first day you may want to change the water...it will be BLACK!

Once you're finished, hose it out & use compressed air to blow all the water out of the fins & internally.
Let it sit in the sun to fully dry.

Done! *MUCH* better airflow, and no more musty smell.
Enjoy your clean evaporator core.

coryc85

Mike - holy cow, that is a ton of info. Thank you very much, very glad you posted. I will most definitely do the hosing down and see if I can get it to cycle. I need to go back to Autozone and get the loaner gauges again, I will do that and hopefully give this test a try on Saturday morning.

Thanks for the parallel condenser info as well. I'm on the fence there. I mean I know it can only help things, but at the same time, do I want to go through the trouble and expense if my real problem is just a weak compressor, a stuck expansion valve or my charge level?

Either way, I really appreciate the advice. With Scope's detailed thread and your hose down test, I might be able to fix this system.

87runner_

iTrader: (1)

Scope...these are great!
Thanks!

coryc85

One more thing Mike, do you think with stock condenser, perhaps new compressor & expansion valve, new drier, all flushed and clean system....and vac'd down and charged up with r134...can I get down to lower than 50 deg vent temps on a 90 degree day?

87runner_

iTrader: (1)

Yes, I believe that is possible.
I have not done it, and I have never done a conversion (I don't believe in them), but that does sound reasonable.

I suggest you have your hoses rebuilt, too. I guarantee they leak.

You may need to borrow a couple of large wrenches: 22, 24, 27mm

Flush out ALL the oil from the previous system, clean your evap well, as I posted, replace ALL the o-rings on the entire system (use the "red" ones from Toyota, they are better!), use a Toyota dryer (put it on last!), fill the system with PAG oil from a new, sealed bottle (PAG oil is very hydroscopic, and don't overfill it with oil).

Don't over-tighten those fittings...just a firm 'snug.'

Put the system on a high vacuum for like 2 hours. (Overkill, I know, but that's what I do.)

Also...if you have that gap between your radiator and the front subframe at the top...go to home depot/lowe's and in the isle where they sell packing for window a/c units you can buy a peace of black spongy foam packing to fill that space...it's only a few bucks. Filling that gap will lower your a/c temps around 5 degrees! ...in my experience.

Another thing you might want to consider is: replace the fluid in your fan clutch, assuming you have a Toyota fan clutch...drain & fill it with 10Kcst fluid...it will pull more air across your condenser. Here in AZ we use 30K fluid. You can buy it from any hobby store that sells RC parts.

You'd be surprised the difference it makes to pull the most air possible across that condenser.

Then, buy a winter coat for inside your truck.

tj884Rdlx

I can only offer additional opinion that R134 will cool my 88 4Runner, i live in Atlanta, and have a very drafty soft top.

I went to an auto a/c - specific shop when my r-12 system stopped blowing cold and freeze-12 + stop leak didn't work as an effective band aid anymore.

It was the shop that convinced me to convert. I didn't want to. But that was 5 years ago and I've not really had a problem with it blowing cold enough.

(My problem has been with it blowing hard enough. Sometimes i have to stretch my leg over and kick the bottom of the blower fan to get it to come on. But that's another story...)

grumpin

Lot's of good info. already. I used R134 and I'm happy with it. I had to replace the condenser and of course the receiver/dryer. Replaced all the o-rings and added the amount of oil the FSM stated, when replacing those two items. I used PAG 46. I had the vacuum on for, IIRC, 45 minutes to an hour. Closed the valve and let it sit for an hour for a leak down check. It was about 95° where I was at last Saturday, and sitting in the sun. The 4Runner was hot. Once I got going down the highway, cooled down nicely. I researched a lot for info. since it had been awhile since I had serviced an A/C system. I also used scope103's thread as a reference. The only thing I didn't do was pull the evaporator. I was concerned, but it is fine so far. Occasionally I will get a "musty" smell. I didn't like or agree with stopping the use of R12, but if serviced properly I don't think there is that much of a difference.

87runner_

iTrader: (1)

SPECIAL NOTE...

PLEASE, PLEASE, PLEASE .... DO ... NOT ... USE ... 'stop leak' in your A/C system.

That $h!t should be banned!!!

coryc85

Thank you both for your inputs. I think this thread has given me enough hope that with stock components I should be able to be comfortable in the truck, maybe even drive it to work with a pair of pants on and not get soaked with sweat!

Step 1, I'm gonna follow Mike's advice and see if perhaps I can tell anything from the soak down test. Maybe it points to a weak compressor, or heck maybe my expansion valve is stuck.

After that, I'll decide whether to purchase a new compressor or not. The expansion valve, drier, o-rings, and shrader valves are all getting replaced for sure. The AC hoses I don't know about. Just checked on a couple of sites and those lines are nearly $100 each. Perhaps I can find a local place to crimp up some new soft parts, I'll try to find a place and see what that costs.

Thanks for everyone's inputs so far. I like that a lot of you are talking about 90 degree weather, that's what I'm dealing with. I usually start a little sweat just walking to the car and I'm very used to parking in the shade and putting the sunshade up in the window just to lower those temps a tiny tiny bit.

mwisham

I agree with 87 runner especially about the stop leak. Never put that crap in your A/C system. If it is leaking, FIX THE LEAK!!!. Also, in south Fla your gauge readings should be around 35 on the low side and 250 on the high side depending on the ambient temps. The low side presssure is a very close approximation of your evap temp. I have converted several R-12 systems to R-134A and you can get very close to the same results with R-134A. I believe all this crap about global warming is BS anyway. Watch out for the coming R-1234 it is about $75 to $80 per pound.

catwrangler

iTrader: (1)

I have a 93-4r. The compressor was shot and the system was empty. It had R134 fittings so someone probably tried to do a conversion on it before I bought it.
I Bought a $65 new compressor off ebay, $120 for a vacuum pump and gauges on Amazon,a new drier and expansion valve, o ring kit. I pulled all the components and blew them out, put it all back together and pulled a vacuum for an hour, then let it set for 48 to check for leaks.
I used R152a(Duster), don't remember the readings on the gauges, used approx 2 cans.
Mid to high 80s, high humidity, got really cold. I am very happy with the results, and it is cheap to recharge if needed.
There are many examples on forums of people using the r152a with success....just an option to consider.

coryc85

Thank you both for your replies. Looks like a lot of people are fairly happy with their conversion.

coryc85

Well, I started to make at least a little bit of progress. Mike suggested that I should change out the fan clutch fluid and it would make a big difference in the amount of air moved across the condenser. So I got on Amazon and ordered some 10000 cst silicone fluid and while I'm waiting for it to arrive, I took my fan clutch off and opened it up. That old fluid looks and feels like honey.





Thanks to Mike for the push. I'm going to do the hose soak on my condenser after getting the fan moving as much air as possible.