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1993 Honda Accord change to R-134a

infj23 on Wed August 27, 2008 6:58 PM User is offline

Year: 1993
Make: Honda
Model: Accord
Engine Size: 4 cyl

The A/C system on my '93 Accord has worked well up until a few months ago. The car has been mine for 2 years so I am uncertain what the history of the system is. Recently, it started blowing hot and pressures were low. I charged the system with a can of Freeze 12 and the system worked great again but is now blowing hot. So, it seems I have a leak that I need to fix.

My plan is to flush the system, replace the accumulator, replace the seals, draw a vacuum, charge with nitrogen to check for leaks and dry things out, draw another vacuum, and charge with R-134a with fresh oil.

Questions: for this system, what oil do I use and how much of it? Also, how much R-134a will this system need and what pressures should I hope for? Anything else I need (does this system have an orifice tube or is there any other new part I need to get?)?

Thanks to all!
Doc

Edited: Wed August 27, 2008 at 7:00 PM by infj23

mk378 on Thu August 28, 2008 10:49 AM User is offline

Find the leak first, as you may need to order a part to replace whatever is leaking. Then you can do the whole job at once.

infj23 on Thu August 28, 2008 6:54 PM User is offline

mk378,
Roger that, but how much oil and R-134a will I need to get the job done?

Thanks again.

webbch on Fri August 29, 2008 5:47 PM User is offlineView users profile

I wouldn't go changing to 134a without also putting in a parallel flow condenser. I have a '92 accord sedan with R12 and while the vent temps are great since I finally recharged it a couple months ago, the "cooling effect" is pretty marginal IMO. I can clearly feel a stream of air coming from the vents, but I personally feel that the blower doesn't blow enough air to make the interior comfortable (obviously a trade off with evaporator/condenser sizing). Riding in the back on a hot day (110 °F) is unpleasant for sure. Even as the driver, it's not all that great.

mk378 on Fri August 29, 2008 7:24 PM User is offline

The NAPA book says 30 oz R-12 and 4.5 oz mineral oil for a 93 Accord. If you're going to convert, use ester oil so you can go back to R-12 without changing oil again. Finding the proper charge for a converted system requires some trial, but the one absolute rule is you never use more R-134a than the R-12 spec called for.

The Honda systems were never overpowering like GM or Ford built but you might check for cloggage of the evaporator or fan. Leaves go under the cowl, then since there's no cabin air filter, they get mulched by the fan and caked in the evaporator.

infj23 on Sat August 30, 2008 12:36 PM User is offline

Thanks to all. Please fill in some gaps for me on a "parallel flow condenser." Any particular part number that would help me find the right one? Does adding a condenser mean that more refrigerant is needed? Does the parallel condenser come with the necessary connectors to hook it all up?

Thanks again.

Chick on Sat August 30, 2008 9:18 PM User is offlineView users profile

You will need to make lines up for a universal parallel flow condenser. You can charge to about 80 to 90% of the R12 charge, then tweak it by adding an ounce or so at a time until your vent temps stabilize, and do add slowly allowing the system to stabilize, this is where many make the mistake. Take your time.. In the end, the outlet, or suction line, should be cold right back to the compressor. As said, it's trial and error, just take your time after getting the 80% in, your car is just about ready for R134a from the factory..as far as capacity..Make sure the condenser is clean, as well as the area between the condenser and radiator, cooling system working properly etc.. Try to keep the high side aroun 2.2 to 2.5 times ambient temp with the condenser fan running..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

infj23 on Sat August 30, 2008 9:44 PM User is offline

Thanks, Chick, mk378, and webbch. I'm in the middle of the job now. I have removed the evaporator. It was a bit trashy with pine needles and such but not horrible. I'm cleaning it now. I'm going to try the job with the existing condenser--if it doesn't seem to perform well and I can't find any other issues, I'll go to the parallel system.

Before reassembly I'm flushing all components with paint thinner.

Now for my pressing questions:
*I see the expansion valve on the side of the evaporator. I'm assuming I need to disassemble those parts to replace the o-rings. Is this a good time to replace the expansion valve, or is the 15-year old one likely good, or what?
*When is comes time to install the oil, where is the best place to put it? Draw it in to the low side port or pour it in somewhere else?
*My plan is to draw a vacuum for about 30 minutes and then let the system sit with gauges to make sure it hold vacuum. Then, I'll charge it with nitrogen and makes sure that hold for a while. Then vacuum again. Good plan?

Thanks again to all!
Doc

Chick on Sat August 30, 2008 9:54 PM User is offlineView users profile

After all that work, I would change the ex-valve and drier now. Add the oil anywhere, drier would be my choice if the system isn't being flushed, id it is, add a couple ounces to the compressor, and the rest anywhere you can. You don't want a dry start, but the oil will be thru the system in seconds when charged..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

infj23 on Sat August 30, 2008 11:00 PM User is offline

Thanks, Chick. I am flushing the system and can add the oil to the drier (the thing I've always called an accumulator, right?).

Hopefully I'll have the job done tomorrow. I'll post the final result when done.

Thanks!!!

Chick on Sun August 31, 2008 5:45 AM User is offlineView users profile

Yes, expansion valve systems use a drier on the high side, O tube systems use an accumulator on the low side. Be sure to add oil to the compressor before starting it..Hope this helps..
Good luck

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

infj23 on Sat September 06, 2008 3:36 PM User is offline

Job Done!
Thanks to all for the help.
The leak in the system turned out to be a crack in the pressure switch. After replacing all o-rings and flushing the components with paint thinner, the system held vacuum and overnight held a nitrogen charge.

When installing the refrigerant, my low side connector started causing me trouble after the first can was in. I used a different connector to get in the second can. Because of this problem, I don't know a low side reading. The high side gradually went up to 170. My initial target was Chick's recommendation of at a high side of 2.2 times ambient (175).

Ambient was 77. After the second can went in, center vent temp went as low as 47 and settled at 49. Nice temperature drop!

I was expecting to put in about two and a half cans (30 oz), but at 24 oz it looks like I might be done. Once I get a better low side connector I'll check both pressures and see how it is really working. But it's hard to argue with a 30 degree temp drop on a 15-year old system designed for a different refrigerant.

Once again, thanks to all!
Doc

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