jacked_72

I posted this in the wrong year forum earlier. Sorry for that--and on my first post!

I bought my daughter a 88 V6 (3vz) 4runner recently. The AC was not working, so I was going to try charging it up to see what we had. It is a R12 system, so I got the retro fit fittings and the the pag oil and started in. I put a vacuum on it and then started the charging. Happily, I saw the compressor clutch engage after, but immediately it started shooting sparks; compressor was siezed.

Ok, got a new compressor (and oil) and accumulator/dryer. I flushed condenser and the lines. I did not flush the evaporator because the expansion valve is in that unit and the flush solvent I used said not to flush the expansion valve. Vacuumed the system, then charged it.

The car does not have a sticker to say how much freon the system holds. I went on line and saw that the 1988 4runner holds something like 29 oz. Doing the 80-85% reduction for 134a, I put in 24 ounces of 134a. The system was definately cooler than ambient, but not by any stretch cold.

I did some readign of FSM for Toyota and read for one of the later years that manifold guages should be reading in the 22-35 psi range on the low side and something around 200-225 on the high at 1500 rpm. I hooked my guages back on and saw that while my low pressure was around 50psi at idle, at 1500rpm, the reading was something in the low teens. So I added additional 134a until I got 30psi at 1500. High side was around 250psi at 1500rpm.

Adding the additional 134a definately assisted with the cooling. Driving at 1500rpm, the AC is cooling to about 30 degrees below ambient. At idle, its doing very little cooling. So, it kind of sort of works, but it's definitely not working as well as it should. The sight glass on the dryer does not show bubbles, but rather a whitish (frothy?) substance going by.

I'm trying to decide where to go from here. My possible culprits are (1) the expansion valve (I did not replace the expansion valve when I replaced the compressor), (2) wrong charge amount (I have no sticker and am just going off of internet information, which could easily be wrong) and (3) dirty evaporator coils, since I didn't pull out the unit to clean the fins.

I'd appreciate it if anyone has any suggestions as to what the problem may be and if anyone still has a sticker on their car saying what the freon charge should be, please let me know. Thanks.

aztoyman

I don't know if it is your problem but, R-12 systems use mineral oil and it doesn't mix with PAG. PAG is used in OEM R134A systems but I have always used Ester 100 in all the retrofits I have done. Ester is compatible with any mineral oil residue. The hoses get saturated with it also. You can't completely clean it out. If you replace EVERYTHING use PAG.

I recently did a retrofit on my 88. Replaced the compressor because it was leaking. Dumped the oil and added Ester 100.

Pulled the A/C unit out and took it apart so I could change the expansion valve and the evap was almost a block of dirt. Cleaned it up and flushed it.

Replaced the dryer with one designed for R134A and while lines were open, flushed them and the condenser. Replaced all the O-rings.

Added correct amount of Ester oil to the system. I don't remember amount. It was listed somewhere.

Evac'd system and made sure no leaks. Added 1st can of R134 and added from a 2nd can until system was cold. I think it took both 12oz cans. It blows ice cold even at idle. I think low side was around 30 psi. High side maybe 250 ish. At idle. Pressures vary with RPM, temp in cab and outside temp. Air flow across condenser. Got cold enough to cycle off.

It goes faster if you stick the can of R134 in front of hot air coming off radiator and squirt condenser with a hose. Raises pressure in can and lowers low side system pressure. I usually stick a fan in front of the truck for some air flow.

Keeping the fan speed on low keeps low side pressure down also. Close the windows and doors.

The sight glass doesn't work with R134 systems.

Your system pressures are going to vary depending on ambient temps and in cab temps. I'm in 100 deg plus temps and my high side may start out at 275 psi with 50 psi low side. The low side will drop as the cab cools down. The high side will drop with air flow across condenser. There is a press/temp relationship. It's difficult to tell you exact pressures.

I keep adding R134 while monitoring temp. Add a little and see how it does. Add some more until it doesn't cool any better and stop. Adding beyond this will actually cool less and your high side pressure will get too high.

I did a ton of retrofits when I worked at a Caterpillar dealership. They had a nice charge/recovery machine that could add or remove refrigerant 1/10# at a time. I found that the systems actually cooled better with LESS refrigerant than what Cat recommended. R134A systems seem to be more sensitive to the charge volume than R-12 was.

If you know you have the correct amount of oil in the system, don't charge with R134 with oil.

Get your system clean, have the correct oil type and amount, evac, make sure it holds vacuum. Take your time charging system while monitoring temp. Stop when it doesn't get any colder.

jacked_72

Any advise on getting the cooling unit out of the truck? I've removed the glove box and taken a look around the box. I see 4 screws holding it in. Does it just pull out or is it connected to the heater core box and the fan by bolts as well?

aztoyman

There are screws holding it in. I don't remember how many. I use a 1/4" drive ratchet, a long extension and a 10mm socket.

You have to of coarse have the lines at the firewall disconnected, and a condensate drain hose comes through the floor into the wheel well. It pulls right off.
Unplug the electrical connector too.

The unit pulls straight back. The grommets around the lines may catch if you don't get them loose from the firewall.

There are screws and clips holding the box together. Just stick a flat blade screw driver in one of the groove areas formed in the clip and rock it off.

You may already know this but just in case, always use two wrenches on the fittings to avoid breaking the delicate aluminum lines.

jacked_72

Frank Torres posted the information below in the other thread I started in the wrong forum. (Thank you Frank.) I moved it here so that its all in one place if someone is looking through these posts in the future:

According with Toyota R12 A/C system retrofit AC002-98 2nd revision

1988 V6 4Runner oil (pag46) quanity is 100cc (3.38 oz.)
R134a charge is 700cc (23.67 oz.)

I would have defiantly removed and flush the evaporator w/ a new expansion valve. Also you may have too much oil causing restriction.

By way of update, I pulled out the "cooling box" and replaced the expansion valve. The box pull straigh back from behind the glove box. There are about 5 10mm bolts/screws holding it in. (Thank you AtoZman.) It was pretty simple to get out.

Anyway, after I replaced valve and flushed the evaporator coil, I'm getting about 40 degrees of cooling below ambient. That's OK for a 90-95 degree day, but its still not enought to really cool the vehicle on a 100+ day. And of course, its blowing 10 degrees warmer at idle, so at 95 degrees, its blowing 65 degrees from the center vent on recirculate with the fan on high. The restriction in the valve did not appear to be gummed up, but I don't know if it was operating (opening and closing) like it was supposed to. There was maybe 10% of the coil covered in leaves and hair. I cleand all of that off the coil.

I'm hoping that too much oil is the problem. The compressor I bought came with 7oz (a little more than 200ml) and I did not remove any of it when I installed it. So I may have 2X the amount of oil recommended in the system. My next thought is to replace the accumulator/dryer again and flush out the condenser coil again. That ought to get a fair amount of oil out of the system, if that is indeed the problem. From a chart I found on the internet, it looks like the condenser will contain about 30ml of oil and the accumulator another 30ml. Draining the system is supposed to remove about 15ml and flushing a line another 15ml. The compressor held about 200ml when installed, I suppose I should be close to the 100ml called for in the retrofit when I'm done.

FrankTorres

Wow, it does sound like too much oil.
BTW, I use denatured alcohol for flushing components.

Good luck...

aztoyman

Sounds like you're on the right track. By the time you are done you will know your system well.

The things that cause us the most trouble are what we learn the most from. Especially if we don't just get frustrated and give up.

Good job and thanks for posting up your progress.

maco35

The a/c temp. on my '87 was in the 40's while driving on the freeway but when i got stuck in traffic, temps. went up between 50 and 60 degrees, well i raised the rpm's on the a/c amplifier, replaced the a/c idle up VSV which was bad and now my temps. are back in the 40's in heavy traffic. or at idle. Also check the condition of your fan clutch which also helps with the a/c temps.

jacked_72

I've changed out the accumulator and removed some oil by flushing. Recharged system and no improvement. I'm getting down to 53 or so driving at around 1,500 - 2,000 rpm, but today was cooler, only around 85 during my tests, so my temperature differential has not improved and got slightly worse.

I thought the thermoister might be bad, but that seems to be changing in value in relation to temperature.

I'm thinking now that there is a problem with the condenser. It was getting dark when I gave up for the night, but the liquid line going into the evaporator was 105 degrees. The line coming out of the AC compressor was about the same. That says to me that there is an issue between the two and the only thing there is the condenser. (Ok, the accumulator is there too, but I just changed that.) I've got to play around with it for another night to make sure the places I'm measuring the temperature are correct (the tubing on the pre cooler was making it tough to be sure in the dark). The pressures seem about right, 25psi low side and 225 high side at 1,500 rpm.

Does anyone know what the temperature of the liquid line going into the evaporator is supposed to be?

I did consider the fan clutch as well, but I think it is OK. The temperature gauge never goes up in traffic and I'd expect to see some overheating signs if it were bad. Besides, moving at 65 mph, I still don't get any additional temperature drop beyond the 53 degree reading at the vents.

aztoyman

Make sure your heater valve isn't leaking by causing your heater core to get hot. It would be like having your heat on at the same time.

Otherwise, if your system is clean and has the correct amount of oil, you have air flow across your condenser, correct charge, it should be cold. The thermistor will cut off the compressor if the evap gets too cold or starts to ice up.

How much refrigerant did you end up putting in? Are your gauges accurate?

I have been bitten by gauges fooling me. Had a charge in the hose and it was trickling in through the Schrader valves. More likely to happen when using large tanks of refrigerant. Small cans are pretty obvious if full or empty.

Just throwing ideas out there. I would play with the charge. If it's getting colder at higher RPM's that is typical of a low charge. The higher RPM's compensate for the lack of volume in the system.

If your condenser didn't have sufficient air flow across it, your high side pressure would be high. If it was plugged internally you would have high pressure issues too. What do you think is bad with it?

I would play around with the charge before I replaced a condenser.

jacked_72

Minor update on my progress.

I tested the temperature going into the condenser and going out of the precooler. There is a 13 degree differential at idle. These temp readings were done in front of the radiator at the grill. It appears to me that the condenser is providing very little cooling. I read that I'm supposed to get a 20-40 degree differential.

The radiator fan is turning, putting out tons of warm air. The car never overheats, even when idling with the AC on for extended periods on a 100degree day. I do not, however, believe that the fan shroud is correct for the car. It fits loosely and blows as much air to the sides as it blows on to the motor.

The fan situation may account for part of the problem, but I still think there is some sludge or plaquing inside the condenser that is causing problems with the heat transfer.

jacked_72

Update:

After duct taping up my broken fan shroud, the AC drop improved. Testing it at night and in the evening was the same, the lowest temperature I could get was 51 and once 50. Whether the temperature is 98 or 90, my cooling ends at about 51 degrees. (Which, honestly, isn't bad for a converted R12 system. My "good" car will get down to about 42 or 44.)

Well, I took it out this morning when the outside temperature was only 80. The ac vent temp dropped to 46 fairly quickly, but as the car heated up, the temperature became 51 regardless of speed, rpm or air flow over the condenser. (I still have very little temp differential over the condenser at idle though.)

My conclusion is that the blend door in the heater box must be slightly open, cracked or just radiating heat. I suppose it could also be a funky thermoister, but I think that is less likely. Is the door metal?

I don't think the heater blend door can be accessed without removing the AC evaporator. Does anyone know differently?

jacked_72

Fixed my a/c idle-up problem yesterday. I didn't realize there was such a thing, but it was bad.

To begin with, the VSV that controls that circuit was bad. With 12vdc across the two termials you should hear a click. (The device is a simple electromatic with a piston that goes up or down via spring depending on whether the electro magnet is on. No click=no good.) I picked up a used one at the junk yard and installed it to the vacuum diaphram device which has the plastic adjustment screw built into it and got nothing. Idle was the same.

I did some digging and looking at the vacuum routing label on the hood and realized that all the tubing routing was screwed up. The VSV had its vacuum line which controlled the diaphram going to the wrong place. The fresh air line that was supposed to come from the air cleaner (a tube from the air cleaner that runs under the plenum) was plugged into a vaccum port on the intake manifold. Also plugged into the same Y-connector running into the manifold was, you guessed it, the other line that was in fact supposed to be there. Basically, the whole thing was under vacuum and there was no air coming in to speed up the idle when the AC is engaged.

Did a little bit of poking around the tubing (and there is a lot of it in that area on a 3VZ) and noticed that the power steering pressure valve has both of its lines plugged into a Y-connector on the tube coming from the the air intake. So, somebody at some point in the past unplugged thes lines and plugged them in the wrong spot.

Anyway, I traded out one of each of the lines and viola, I have AC idle up.

I've also tinted the window and that helps significantly with the heat build up in the truck.