A/C Retrofit and O-rings and sensor

Menoxz

New member
So I'm in the middle of fixing a leak I had in the evaporator on my st185, changed the O-rings according to TSB, Also flushed the system from mineral oil to POE since I'm going to use r134a, thing is one O-ring was crap at the drier and I tried putting in a HBNR from a kit, but it didn't seal, probably because it was just a teeny little larger.

I can only find the O-rings for the evaporator. Toyota doesn't show up the o-rings for the rest of the system, anyone that has done a retrofit, how did you do? since neither the Gti and GT-four have part numbers for the rest of the o-rings.
I'm considering going to the nearest Toyota dealership and check if they have some o-rings in the same size from something else. "Worst case" I'll just have to order an o-ring kit from US which should fit?

Also at the coolant neck there is a broken A/C sensor 8862520300"THERMO SWITCH ASSY" that is removed on later year. Should I permanently ground it or not? It's temperature controlled switch and the a/c only works hard when it's ground. I've tried reading electronic diagram without avail about it, though my Diagram-fu isn't that great. supposedly it has something to do with overheating protection?

Thankful for answers
Adam
 

Roreri

Active member
I am kinda in the same boat--probably going to just replace the compressor and receiver dryer when the current refrigerant charge escapes.

Though the compressor and receiver drier I have on hand are said to have o-rings with them, I got this o-ring kit in preparation for the job, in case I have to use them--would these be in line with what you're looking for?

https://shop.advanceautoparts.com/p/fac ... 15890327-P

AC O-Ring Set.JPG
 

Menoxz

New member
Yup. That's the last resort. The toll and shipping time and costs are the things that are stopping me.
 
Don't know if this helps or not, but the ST185 evaporator & expansion valves have o-ring part numbers listed. Are the o-rings you used on your replacement evaporator the same size you need for your receiver/dryer? Did you keep your old o-rings removed from your old evaporator to see if they are the same size needed for the receiver/dryer?

We have a new receiver/dryer from Toyota in a box as a spare for the ST185, and it has o-rings in it. So worst case, get a new receiver/dryer and you will have the o-rings you need. It's often best to replace the receiver/dryer anyway, if the A/C system has been exposed to the atmosphere for any period of time, or doing a refrigerant retrofit as you are doing.
 

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Regarding the Toyota P/N 88625-20300 (Thermo Switch Assy), it sure looks like that particular switch is specific to ST185's from 1990-1991, as you stated. Discontinued, of course. Will be hard to find. There is a thread going back to 2011 when the thread originator was able to purchase one new: viewtopic.php?f=10&t=42290

On a side note, the 1990-1991 Celica's with the 5S-FE engine apparently used a thermo switch assy also. It was Toyota P/N 88625-20290. Not saying these are directly interchangeable, but I wonder if the 88625-20290 is physically interchangeable with the 88625-20300, and maybe has a slightly different switching temperature. That might be an option, and while they are all discontinued from Toyota, there would be much greater availability of the 88625-20290 from salvage 1990-1991 Celica's w/5S-FE's in salvage yards to get one from to see if it might actually work for you.
 

Menoxz

New member
93celicaconv":1w1eracd said:
Don't know if this helps or not, but the ST185 evaporator & expansion valves have o-ring part numbers listed. Are the o-rings you used on your replacement evaporator the same size you need for your receiver/dryer? Did you keep your old o-rings removed from your old evaporator to see if they are the same size needed for the receiver/dryer?

We have a new receiver/dryer from Toyota in a box as a spare for the ST185, and it has o-rings in it. So worst case, get a new receiver/dryer and you will have the o-rings you need. It's often best to replace the receiver/dryer anyway, if the A/C system has been exposed to the atmosphere for any period of time, or doing a refrigerant retrofit as you are doing.

I only bought the O-rings for the evaporator and expansion valve P/N 90099-14045 and 90099-14044 Brown O-Rings. One is too large in diameter and one too small for the pipes for the condensor and reciever/dryer. I didn't receive any O-rings with my aftermarket receiver/dryer when I bought it only the unit itself. So I guess only OEM Reciever/dryer gets the o-rings.

I will check with my local toyota dealership if they have equivalent O-rings, Maybe check the price on the dryer, suspecting it will cost at least around 150$ since it's Sweden.
 
Why don't you take the old receiver/dryer o-rings with you to an auto parts store that sells vehicle A/C system o-rings, and match them up to what the store has. I would think your chances of finding exactly what you need would be quite good.
 

Menoxz

New member
93celicaconv":18dfseod said:
Why don't you take the old receiver/dryer o-rings with you to an auto parts store that sells vehicle A/C system o-rings, and match them up to what the store has. I would think your chances of finding exactly what you need would be quite good.

Good idea, will take it with me tomorrow, Also looks like the Thermo switch is an overheating protection for the coolant system? It goes into the A/C Amplifier. Gonna give it another try to get the wire in contact with the sensor. since it snapped at the base, otherwise gonna try GT4 Heaven since no junkyard had the part for 5sfe.
 
Let me know your progress. Finding any 5th Gen Celica's in a salvage yard these days is getting difficult. One salvage yard near me had many years ago, still has a few. But looking for a 1990-1991 5th Gen with the 5S-FE narrows things down a lot. I'll check if one or more are out there yet the next time I visit it.
 
I actually took a run out to the salvage yard I typically go to today, for other needs involving 5th Gen Celicas. On this subject, there was a 1991 Celica GT 5S-FE in the yard - but the water outlet assembly with all the sensors was already removed. So no luck today helping on this subject.
 

Menoxz

New member
Went to toyota today, bringing the reciever/dryer was an excellent idea, they tried finding o-rings that fit the holes, so they gave me two black toyota HBNR and two green universal HBNR rings, gonna try fitting them maybe tomorrow, will try to measure them also.

Also I checked the price on the reciever/dryer and it was 130$
 
Wow, the prices from Toyota have shot up a lot. Hopefully the Toyota dealer in the parts department got you the right size o-rings for your needs. Probably best to use the greens ones if both sets fit - I think those work with any refrigerant (just in case you retrofit now or in the future to R134a).
 

Roreri

Active member
I know you will probably get raped on shipping but try sparkplugs.com for the receiver dryer. They purvey Denso parts.
 

Menoxz

New member
Soo, I decided to check on the A/C Water temp sensor, since it's an simple overheating protection sensor for the coolant system.
In case the water temperature starts going high it will reduce the output from the A/C Compressor to keep temperatures down, I don't know how they changed it on later models.

Anyways, since the cable was ripped at the base I started to cut away some of the insulating materials to expose the connector on the sensor, fluxed and soldered back the cable, and welded some plastic over it, works for now.

As for the O-Ring for the reciever/dryer, I got some O-rings, but the technician was looking on the wrong mating surface for the o-ring, but 90099-14044 was the same size and it's not leaking

So
90099-14044
1 for Expansion valve, 2 for reciever/dryer

90099-14045
1 For Expansion valve, 2 for Evaporator.

Since you need to remove the "Pipe, cooler refrigerant liquid, a 88716A" there is a risk the O-ring on the condensor will crap itself, I changed to a HBNR that fitted from my kit, it was slighty beefier but it worked and the connector seated flush.
 

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Menoxz

New member
Already done it. Flushed Most of the mineral oil from the system. Added POE. Drew vacuum and the r134a. Blows cold air. Will see how good it is when the real heat comes.
 

Roreri

Active member
Good, good!

Did you just use plain r134a?

I was looking at the self-help A/C charge offerings at the local parts store yesterday. One of them, the can made a claim that it could seal most leaks. Given that I have a small leak at the compressor--so small that a charge can last for months--I admit I was tempted to get it but I also know that these kits can (will) gum up the works and clog pipes.

I will be replacing a compressor and receiver dryer later this year, so I'll be doing this journey myself. I definitely want to learn more about what's involved with flushing and filling and charging.
 

Menoxz

New member
Roreri":3ptqzuh9 said:
Good, good!

Did you just use plain r134a?

I was looking at the self-help A/C charge offerings at the local parts store yesterday. One of them, the can made a claim that it could seal most leaks. Given that I have a small leak at the compressor--so small that a charge can last for months--I admit I was tempted to get it but I also know that these kits can (will) gum up the works and clog pipes.

I will be replacing a compressor and receiver dryer later this year, so I'll be doing this journey myself. I definitely want to learn more about what's involved with flushing and filling and charging.
Yup, plain r134a 700 grams.
Most leak seals are temporary fixes with issues down the line, it makes the o-ring swell. I don't remember what the cons of it are,I suspect it affects the o-rings in a bad way and all the parts in the A/C System.

In the US afaik, there seems to be ready kits for flushing the A/C system with compressed air and a special solvent, that or let someone with a flushing machine flush the system. I heard someone nearby me had such machine, but I decided to do it myself anyways. I like fixing things myself so I know what has been done, and if it fails, I know why it failed.

I used denatured alcohol and some silicone tubing to flush most of the oil out of the system, since it evaporates and doesn't leave residue. Supposedly pure mineral spirits/low odor? should work "better?". Aceton is the best apart from real A/C solvent, however it attacks everything and as you know, is aggressive against everything, so there is a risk of ruining o-rings.

However when It came to the compressor I simply took it out of the car and turned the wheel to get most of the oil out. As the sight glass is cloudy, which shows I didn't get all the old mineral oils out, could have done a better job. I used this formula for oil amount and used using vacuum to draw it into the system, should had added it before installing the compressor Adam!

45 ml for condenser
45 ml for Evaporator
15 ml for each hose line flushed
15 ml for receiver/dryer
121ml for compressor

Toyota specify to use ND8 oil which is pag46. I opted to use POE since it's "retrofit" oil, supposedly PAG oil is more aggressive on simple nitrile o-rings rather than on HNBR rings, allthough the difference between O-rings was only the temperature rating in the end? I don't know which material toyota uses for the brown/red O-rings, I make the assumption it's nitril. Other materials might not fare well with PAG Oil

Should it leak again I might opt to get it flushed from the guys with the machine.
 

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