Where to evacuate AC ?

[knl25]

I'm replacing the high pressure hose and the accumulator since there's a leak.

Can anyone please post the procedure of evacuating the system after I put new parts in (which port?)?

I planned to evacuate it with a vacuum pump, and then top it off with R134a. Anything else I should be aware in doing this?


Thanks

[12Ounce]

My personal preference is this:
(Prefill system with lubicating oil if necessary.)

1. First hook up a filler hose assembly; complete with gauge, trigger valve, and a can of R134a; to the low pressure port.

2. Hook up vacuum pump to high pressure port and begin evacuation. Early on, after most of the air is removed, I trigger just a wee bit of R134a refrigerant into the system. This helps to purge air from the filler hose and the ac system. Continue to evacuate for the recommended period ... usually hours. When evacuation is complete shut off inlet valve on the pump.

3. Before disconnecting pump, empty much of the can of R134a into the system. Continue until you can see some reading on gauge ... just a few lbs above "atmospheric". You can now disconnect pump as the system is pressurized and there is little chance of air getting sucked back into the system.

4. Continue to fill with R134a refrigerant while idling engine.

[tomj76]

1) Draw vacuum. It can be done from either port, although I've always used the low side port.

2) Make certain it holds vacuum. Normally the vacuum pump is connected to the system through a refrigeration manifold with gauges. The low side gauge should have a vacuum reading. After drawing a 'decent' vacuum (15-20 mins) and closing the manfold valves, the vacuum should remain high (29-30 inches vac). If it decreases (less vac) then there either is a leak, or there is some residual liquid boiling off. A leak generally has a more-or-less steady rise with time, while liquid boiling off (i.e. H20) will be rapid at first then taper off. If there is no holes in the system, then proceed to the next step.

3) It's important to remove all the water vapor. Water vapor in the system can condense on the expasion orfice, freeze and clog the flow of refrigerant. Since the boiling point of water in a near vacuum is still somewhat higher than most ambient temperatures, to improve the amount of H2O that has a chance to boil, I've "charged" my system with a vacuum, then used the car for a few days to allow the engine heat to heat up the AC components. Then I've drawn vacuum again. This is also helpful in making sure there are no leaks.

4) Most charging setups incorporate a means of charging the system without disconnecting the vacuum pump AND allowing the line between the refrigerant source to also be evacuated (to avoid putting any air into the 'clean' system). This is commonly done by putting the pump on the high pressure hose, putting the refrigerant source on the 'common' hose, and connecting the low pressure hose to the low pressure port. Using the manifold valves you can use the pump to draw gas from the system (and from the refigerant line), or add refigerant to the system without disturbing the vacuum pump connection. While there is a vacuum in the system and after clearing the charge lines, put a small charge of R134a into the system. This will help dilute any remaining air in the system. I only put enough in to get to ~ 0 psig. Pull vacuum again then repeat.

5) Now that you've fully cleaned out the system, empty each can of R134a into your system for the proper charge. The charging should be done only on the low pressure side. When the A/C pump is running the high side pressure can rupture the cans. It's necessary to run the A/C while charging (after the intial charge is added) to lower the pressure and allow the R134a to be drawn into the system. Weigh the cans before and after to determine the amount of charge that has been added. A digital bathroom scale will get you within 2 oz of the right charge. If you have a more sensitive scale, I'd use that.

Make sure that you replace any lubricant lost due during the discharge or refrigerant and the replacement of parts. It might be necessary to replace the dryer charge as well, if the system has been open to the air for a significant length of time.

[knl25]

thanks for the quick and thorough response guys.

i will start when parts arrive and will update.

[knl25]

I replaced the high pressure hose and accumulator because I saw oil stains on the hose at the bottom the condenser. After evacuating the system and recharging it to 37 in low pressure port and 180 in high pressure side, I heard low hissing noise in front at the radiator area. Does this sound like the condenser is leaking? How difficult is it to replace the condenser myself? Does it slide out easily after disconnecting it from the hoses? Or Does it involve taking the radiator off? Also, I see that rockauto has Spectra Premium and Proliance brands for much less than Motorcraft. Anyone has experience with these brands?

Thanks

[12Ounce]

On my '99, there is a removable sheet metal "trough" that goes beneath the radiator and condensor coil.

Remove the front bumper cover. Tie the radiator at the top with large plastic tie-wraps. Remove the trough and drop the condensor coil downward.

[tomj76]

The simplest way to find a leak is to pressurize the system then a paint brush to apply a strong solution of soapy water to potential sites for the leak. You should see soap bubbles when you isolate the leak.

I've used compressed air instead of refrigerant to pressurize the system, since it's less expensive and evironmentally friendly. The experts use dry nitrogen since it doesn't inject water vapor into the system. However if you have a leak then there's already water vapor. You need to isolate the leak in order to avoid buying unnecessary parts (i.e. the hoses).

I haven't pulled the condensor on my Windstar, but I believe it should be possible to get it out without removing the radiator.

Also, if you have a leak that you can hear, then I doubt you were able to pull a very deep vacuum, maybe 15 inches at best. The vacuum has be better than 29 inches or the air in the system will keep the A/C from working, or possibly even destroy the compressor.

EDITED TO ADD:
I didn't realize that you had run the system to charge it. If this was after shutting down the engine, then you may have only been hearing the gas 'leaking' across the expansion orfice. Do you have evidence (i.e. dropping pressure levels and/or dropping temperatures over time) of a leak?

[knl25]

The vacuum gauge was at maximum by the blue gauge(around -30inHg i think) after 1 hr evacuating with a 6cfm vacuum pump. The problem is I don't have compressed air nor nitrogen source to test with the bubling method.

[tomj76]

OK, maybe the leak is smaller than I'm imagining. Are you sure there's a leak? Are you sure that what you're hearing is a leak?

[12Ounce]

If the oil stain was on the hose ... it's likely that the pressure sensor in that hose, or even hose fittings, ... is the culprit, not the condensor. I've replaced one of those sensors ... that was a slow leaker.

[knl25]

It took me 4 hours to replace the condenser. That was a lot of work. There was a large oil stain spot on the old one and it runs fine now.

After evacuating the system for an hour I put 3oz oil + 6 bottles (340g) of R134a and the pressures were about 40/175, which seems low. Anyone know the capacity for the 2000 LX?

Thanks

[knl25]

found the answer to my question : 56oz (w/ aux)
http://fcsdchemicalsandlubricants.co...arge%20cap.pdf