defrag4

Found this on ebay, comes with the pressure gauge so you dont overfill, my 87's AC doesnt blow cold

http://cgi.ebay.com/ebaymotors/R-12-...Q5fAccessories

I had read about people having success with just replacing the R12 caps with the R134a caps and filling the older system with r134a.

This is a knock-off R12 similar to Freeze-12

I am going to try this first rather than do the cap conversion.

Anyone use on of these before?

1styota4X4

no i just replaced the dryer and had teh system vacuumed down and filled with R134...cost me 40 bucks or so

thralldad

o-rings probably need R&R with the dryer. Then vac and recharge.

myyota

R12 and R134 are not compatable with each other, so don`t mix the two together. Your better off staying with R12, it gets colder than R134.

JamesD

Not true necessarily. Depends if you do the conversion correctly, it will blow just as cold as R12. The correct way to do a conversion is to change the dryer, drain all of the oil out of the compressor, refill it with ester oil, vacuum and charge system. You could substitute the ester oil for PAG oil if you decide to replace the dryer but if you keep the dryer then use ester oil. Ester oil is compatible with R12 and R134a. PAG oil if for R134a only. I have done many systems by draining the compressor and filling it with PAG oil without changing the dryer with great success, but that was the customers choice not mine. But I still HIGHLY recommend changing the dryer. I have on all my personal vehicles.

James

tim a.

2 cans of r12 cost me 50$ on ebay.Why convert?

yeehaw1

Because for $60 bucks at napa you can get a retrofit kit for these trucks that includes all new seals, nozels, and the ester oil, and be paying around $7 for 2 cans of r134a! (price for r134a guesstimated, haven't bought any for a while)

at Jamesd =

tim a.

Guess thats ok if you like close to cold.

tim a.

I feel for ya.My r12 setup blows 38 to 40 at the vent.I have actually fogged the outside of the windows because its so cold.With the price of r12 nowadays,I can see no reason to convert.I have put 36oz of r12 in my truck in the 18 years I have owned it.If r12 skyrockets in price maybe I would consider it,but not now.

defrag4

Ya I think I am going to stick with R12 for now, ordered that kit off ebay, will report back with results

defrag4

Im pretty sure my system is drained, what maintenance should be done before refilling with the system? I tried searching A/C compressor seal replacement but could not find anything?

tim a.

you should do a leak test and evac for at least 30 min before recharge.prefererably 45 min.gets all the moisture out.if system is airtight fill her up.make sure you cycle your fan clutch on when you recharge.keeps expansion valve from freezing up

cursmello

I found some r12. Whats max hi side press on compressor? 165 psi hi side seems kinda low and im getting 58 degrees at vent.

scope103

Based on what?

If you're using a pressure gauge to estimate fill, you need the pressure AND TEMPERATURE on both high and low sides. One pressure reading tells you next-to-nothing.

This might give you some leads: https://www.yotatech.com/forums/f116...-r134a-284801/

Janos01

Honestly, if your able to still find r12 at ok prices & if your A/C compressor is working fine, then I would not mess with it. I agree with myyota & tim a. R12 is way colder than current freon and if the price for it is still ok when you find it, why convert? If your system is empty, I would recommend finding some r12 with a color die so you can see if there are any leaks which will prevent you from charging your system every so often.

rustypigeon

The R12 system should read 21-28psi on the low side, and 206-213psi on the high side. This is with the engine at 2000rpm. Ambient air temperature may slightly vary the pressure indications, but this is the ballpark pressure readings.

scope103

Rustypigeon: do you have a reference for that?

According to this PT chart http://www.foxmacon.com/Tecumseh/Tem...re%20Chart.PDF,
R12 at 206psi corresponds to a temperature of 140°F. Are you measuring the pressure BEFORE the condensor?

A suction-side pressure of 28psi corresponds to a temperature of 30°F AFTER the evaporator, which means that very little "cold" is being released to the cabin. (The refrigerant only gets warmer in the evaporator; if the temperature inside the evaporator is below 32° at any point the evaporator should be one big block of ice. Except (maybe) in the Sahara.)

I'm by no means an expert in refrigeration, but those numbers are hard for me to follow.

rustypigeon

The reference I am using is the Toyota FSM. (page AC-12)
http://personal.utulsa.edu/~nathan-b.../8inspecti.pdf

These are the expected pressures at the service valves with the compressor running.

The chart you are referencing seems to be static pressure values with the compressor not running. The values on your chart are what you would typically see on both high and low side with the engine shut off. For example a typical 134a system will have a system pressure of 72-114psi when the engine is shut off. This corresponds to an ambient temperature of 70F-95F on the chart you linked.

You can't use the static pressure of a refrigerant to determine if the system has an adequate amount of refrigerant, it will only tell you that some liquid refrigerant is present in the system. For example at 80F R12 has a static pressure of 84psi. If you hook up your manifold gauge and get a reading of 84psi with an ambient temperature of 80F, you have some liquid refrigerant in the system. It could be only 1 ounce, or it could be filled to spec. There is no way to tell with a static reading. If however you get 50psi static with that same 80F ambient temperature, you know the system is low because no liquid refrigerant exists in the system at 50psi with R12 at 80F.

cursmello

Whats the subcooling need to be? Filled to 165 hi side, 32 low. Liquid line temp 95. I now know u dont want more than 220 psi hi side. So whats good high side pressure at 80 degree ambient? It may be 110 outside in august.

rustypigeon

Are you measuring your pressures at 2000 rpm, vent set to recirc, and fan on high? The pressures I gave you are valid with an air inlet temp of 86F-95F.

If you are getting 32/165 with the above conditions, your compressor is worn.