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wild03
08-31-2014, 02:41 AM
Hi all,

I'm trying to troubleshot a not so cold AC issue on a 1992 celica ST. 1.6L

my brother and I did the a134 conversion more than 10 years ago, no problem since.

We have determined that the compressor is not pulling optimal pressures so it will need replacing.

But we noticed the condenser fan not running at full speed when AC is on.
my brother says that the condenser fan should run at full speed when the AC is on because back in 1992 they didn't have dual speeds, right now the fan sometimes is LOW and sometimes HIGH. is this normal? does these cars have dual speed fans?

Thanks in advance.

METDeath
08-31-2014, 03:30 AM
Before you go replacing parts, are you possibly low on refrigerant?

wild03
08-31-2014, 04:24 PM
Thanks for the prompt reply. BTW celica is an ST

Brother is a mechanic by trade, he hooked up the gauges and he said this was not the case. he said that the pressures were not where they should be.

Ebay has the compressor for $68 which is incredible. It has no clutch, is this hard to swap? I have puller and I'm sure brother has other tools at the shop.

Thanks.

http://www.ebay.com/itm/New-A-C-AC-Compressor-Toyota-Celica-97-96-95-94-93-92-91-90-Corolla-89-88-Truck-/370624873543?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1992|Make%3AToyota|Model%3ACelica|Subm odel%3AST|Engine+-+Liter_Display%3A1.6L&hash=item564af6c447&vxp=mtr

4thgenceli
08-31-2014, 05:07 PM
If it's a dual speed fan there'll usually be 3 wires and not just 2.

Sent from my SM-N900V using Tapatalk

wild03
09-01-2014, 03:56 PM
If it's a dual speed fan there'll usually be 3 wires and not just 2.

Sent from my SM-N900V using Tapatalk

Thanks, There are 2 wires on this fan. my guess is that they could be pulse modulating the signal and still get away with two wires.

I get the same voltage of a little over 13v regardless of whether it is running slow or fast.

I find it hard to believe that a fan could behave this way, Run fast for a minute, then slow for a minute, then fast. If the winding was bad it would not change speeds like this. if brushes were bad it would not run at full speed whenever the fan is connected directly to the battery.
If the fan was bad I would expect it to run slow at all times and maybe speed up if hit with a hammer or something.

I could run it from the battery for a good 5 mins, if it remains at full speed at all times then that might prove the fan is good.

thoughts?

93celicaconv
09-05-2014, 01:06 AM
A 1992 Celica GT-S has 2 fans, normally called a radiator fan and a condenser fan. Both fans are dual speed - 2-wire units. Intriguing question. When the A/C compressor is engaged, a set of relays causes both fans to be in series, so the voltage across each fan is half the line voltage (or 6 volts), which causes a slower operating speed. If the coolant temp. sensor activates due to a high temperature, the relays activate to ground each fan separately, so each fan has sees full line voltage (or 12 volts), which causes the higher operating speed. So I guess the fans are really single speed, but they operate at 2 different voltages, causing them to act as dual speed.

wild03
09-12-2014, 06:01 AM
Thanks for the info, This makes a lot of sense and fits the observable behavior.

When in series unplugging one fan stops the other.

I already received the compressor and drier and will be swapping them this weekend. I did ordered a fan motor for $45 so I guess that was money down the drain, The good thing is that I didn't cut any wires so I can swap to the factory fan with no issues.

Thanks a lot for the answer.

Gt4grey
10-04-2014, 06:05 PM
How do you convert air con to take modern gas ?

93celicaconv
10-04-2014, 06:55 PM
There are 3 ways, only one of which is long term.

The short-term way is to evacuate the R12, pull the vacuum down the the micron level for seveal hours, then refill with R-134a. Problem with this is the old R12 system used mineral oil. With R-134a, the liquid refrigerant does not mix with the mineral oil, so the mineral oil will settle out and will not be circulated. That means your compressor will fail due to no lubrication.

A mid-level way is to do the same as above, except add in Ester oil. The mineral oil will still settle out and not ciruclate, but the Ester oil will circulate with R-134a. Only problem with Ester oil is that its lubricating properties on the R12 swash-plate compressors is not as good, so the change for a compressor failure goes up.

The best (and most costly) way is to remove the R12, remove the evaporator, condenser, compressor and receiver/dryer, and empty all 4 components of the original mineral oil. Reinstall with new o-rings. Pull a vacuum down in the micron level for seveal hours to remove non-condesible gases (including water vapor that gets in when the system is opened, then add PAG oil, then R-134a refrigerant. This is the best.

Just a note about R-134a, it is slightly less efficient, so your lowest approach temperature will be slightly higher. And it operates at higher pressures, which could cause a weak system (o-rings at least) to fail. Other than that, conversions done this way tend to last a long time.

wild03
10-05-2014, 04:41 AM
A note on the conversion, My brother and I swapped from R-12 to R134 on this car in 1998, WE used the "mid-level" approach, added an oil that was compatible with R12&R134. System worked fine for 16 years, Just recently that the compressor showed low compression numbers and brother advised to change it.

I paid $68 (shipped) for a compressor without clutch for this car on ebay. We swapped the clutch from the old compressor and all is working good so far.

Lets see how long this compressor lasts.

93celicaconv
10-05-2014, 01:30 PM
A note on the conversion, My brother and I swapped from R-12 to R134 on this car in 1998, WE used the "mid-level" approach, added an oil that was compatible with R12&R134. System worked fine for 16 years, Just recently that the compressor showed low compression numbers and brother advised to change it.

I paid $68 (shipped) for a compressor without clutch for this car on ebay. We swapped the clutch from the old compressor and all is working good so far.

Lets see how long this compressor lasts.

This is a good reference point. Given the vehicle you did this conversion on was R12 based, the A/C compressor had some years of service before the conversion (unless you changed it with the conversion). The total life of that A/C compressor is pretty good. Many R12 compressors never fail on the compression side (they can fail by starting to have internal refrigerant leaks). The choices are largely a matter of cost and acceptable life, which is different for every person's situation. Good input!

wild03
10-07-2014, 06:51 AM
This is a good reference point. Given the vehicle you did this conversion on was R12 based, the A/C compressor had some years of service before the conversion (unless you changed it with the conversion). The total life of that A/C compressor is pretty good. Many R12 compressors never fail on the compression side (they can fail by starting to have internal refrigerant leaks). The choices are largely a matter of cost and acceptable life, which is different for every person's situation. Good input!

As far as I know this was the original compressor. We did the swap due to a leak on the evaporator. After buying two aftermarket evaporators both with small leaks at weld points out of the box, we bought the toyota part from the dealer. 3 times the cost but no issues there since.