Our Disclaimer:  IROCZONE.com, its affiliates, owners and members, claim no responsibility of damage to your AC system or any other component of your vehicle as a result of using the following documentation.  By proceeding, you agree that there may be some error in documentation and you will assume all risks from here on out.  We recommend that if any AC work is to be done, that your vehicle should be taken to a local repair shop.  These instructions are for educational purposes to show what is involved in retrofitting an AC system correctly, versus one of those cheap kits you buy at Wal*Mart that don't work worth a dime.

Any questions?  Go back and read the first page again.

Now on with the show.

The following documentation is in very DRAFT mode!  If you have any questions, please do not e-mail us.  We will post updates as we keep working on this project.  We suggest you visit http://www.ackits.com and go to their message board.  You can also visit http://www.aircondition.com and browse through their archives of messages and read, read, read to get a good feel of what's involved and hopefully answer any questions you have.  These instructions are based on the fact that you have some knowledge of auto AC and can go from these.  Once this documentation progresses, we will adapt it with more detailed instructions and pictures to help those who are less knowledgeable than others.

Now that your system has been evacuated or has had the refrigerant leak out completely, we'll start by disassembling the system.

Remove the belt to the compressor, disconnect the lines going to the compressor and remove the compressor out of the engine bay.  This will be necessary to flush out the compressor of the old mineral oil and adding in the new 134a compatible oil.

Remove the accumulator by disconnecting the connector for the pressure switch and the lines going to the accumulator (from the condenser and evaporator).  There is also a couple of screws holding the accumulator in place.  Loosen or remove these, pull out the accumulator.  Go ahead and remove the pressure switch from the old accumulator.  Also, you should probably remove the low side cap and keep it for a spare on something else you may have.  If the new accumulator comes with a new pressure switch, keep the old one for spare.  If not, remove the cap from the new accumulator where the switch will go and install the old switch (use new o-rings and coat them with Nylog before installing the old switch.  You should probably clean it up a little if it's dirty, too).  IMPORTANT:  Keep the accumulator capped up when not in use.  There is desiccant bags that absorb moisture so the less moisture in the accumulator, the better it will perform.

Disassemble the remainder of the system, remove the old orifice tube and flush with AC Flush solvent then blow out with dry compressed air. (Condenser, evaporator, lines).   Do not flush the compressor, accumulator or any line with a muffler/filter in it.

Replace as many O-Rings as possible with 134a compatible O-rings (green mostly). Don't forget the compressor lines!  TIP: Coat the rings with Nylog.

Flush the compressor with new oil in attempt to replace as much mineral oil as you can. This can be done by manually turning the hub of the compressor, while slowly adding new oil.  Which oil you use is up to you. Again, we recommend PolyAlpha+, or Texaco HFC-100 Ester.  When you feel comfortable enough to where you believe most of the old oil is out, place the compressor on a flat surface, back side down (open ports down) and turn the hub a dozen more time and let it sit for a while in attempt to drain as much of the oil out as possible.  Since we don't know exactly how much oil is in there from the flushing, we won't know how much more to add so we'll try to drain it out and start over with the oiling process below.

UPDATE:  It is required by law to install a high pressure cut off switch for all retrofitting to 134a in a vehicle with a manual relief valve. (by licensed repair shops, I'm not sure if it also means the DIY'er).  Since we have never dealt with these units before, it would be best to follow the instructions in the set and work them into this document.  I believe it requires installing an adapter on the high side Schrader valve hence is why I place this update before the following step that goes over on how to install the Schrader valve adapters.  Problem is, I'm beginning to think that our vehicles do not have a manual relief valve as they only sell the switches in 1/4" and 3/16" ports.  Our port is 3/8" .. I thought I'd throw this tidbit in.  If they do sell high pressure cutoff switches for our cars, I'd recommend putting one in to prevent a possible problem with over pressures.

Install 134a adapters. Again, we STRONGLY recommend the brass ones at ACSource.com. If not, get ones with Schrader valves in them that require you to remove the old Schrader valves. Many times, and many cheapie kits will have those aluminum crap adapters that use the existing Schrader valves. Problem with this is that the Schrader valves get old and seals worn and brittle. There will be a pretty good chance of a leak.

Add oil to the system. 1/2 total amount in compressor, 1/4 in evaporator and 1/4 in condenser. This should evenly distribute the oil in the system. Do not add too much as this may be more harmful to your system as not enough. It's about 6oz. total system oil capacity for our AC systems (Harrison R4 compressor).  If you flushed the old compressor with new oil, we recommend using slightly less as there is probably .5oz sitting in the compressor, even after draining.  IMPORTANT:  Do NOT over lubricate your system!  Too much oil is just as bad, if not, worse than not enough oil in an AC system!  Just the right amount should be added to the system.  If too much oil is added, the only right way to fix it is to flush everything out again and start over, so be very careful and precise in adding your oil to the system.  Compressors can't compress oil, so too much oil in a system will cause the compressor to whine.  Not enough oil will also cause the compressor to whine, BUT, there are ways to add more oil to the system after it's closed up - but it's not so easy to remove the oil.  Get it?  Alright, then.

Install the (Ford) orifice tube (where ever the old one was removed from.  Either at the evaporator inlet or condenser outlet) and accumulator.  The orifice tube should go in how the old one was removed.  If you cannot remember, the larger end of the orifice tube (blue end or the end with more screen) faces incoming refrigerant.  If it needs to go into the evaporator inlet, the smaller end goes in first.  If it needs to go into the condenser outlet, the larger end goes in first.

Reassemble the system.  Take care in not over tightening everything.  Most of these parts are aluminum and you would be surprised at how good these connections can be with not-so-tight connections.

Hook up your gauges.  Red to high side, blue to low side, yellow line to vacuum pump.  Start the pump and open up both low and high valves on the manifold gauge set to pull from both ports. Pull for AT LEAST an hour. I recommend at least 3 for a good vacuum charge.

Why vacuum?  Two VERY important reasons why you should pull vacuum on an AC system.  Number one, is removing as much air as possible.  Air in an AC system will cause poor cooling, excessive compressor noise (air is harder to compress than refrigerant) and higher pressures creating a very inefficient AC system.  Number two, is pulling vacuum removes moisture.  Even humid air trapped inside the system can cause damage.  We do not want ANY moisture in an AC system.  Moisture is bad.  The higher the vacuum in an area (closer to 30"), the lower the temperature in which water boils - to below room temperature.  I will try to find that chart and post it here for reference.  Good info!  This is why we suggest holding a vacuum for 3 hours.  Good measure in making sure that ALL of the moisture is boiled out.

Check out this chart.  If we could achieve 29.00 inches of vacuum, then moisture would boil out of the system at 80 degrees F.  The higher the temps, lower the vacuum, the faster moisture will boil out.  For added assurance, try running the engine for a little bit to warm the engine compartment or even park it out of the shade.

Follow these closely: close both valves on the gauges, THEN disconnect the vacuum pump line to the pump, THEN turn off the vacuum pump.  This is CRITICAL as to prevent loss of vacuum.

Install the can tap on the first refrigerant can.  Turn the valve clockwise until it stops.  This will puncture the can.  

Attach refrigerant can tap to yellow line and loosen the yellow line at the gauges. Slowly open the valve on the can to release a bit of refrigerant in the line until it starts to come out the connector at the manifold. (This is to purge the line of any air.)  As it's coming out, go ahead and tighten the connector at the manifold.

Turn the can upside down to charge as a liquid. Open up LOW SIDE valve on manifold. Refrigerant should go right in. Close the low side valve at the gauges. Remove the tap from the empty can and prepare the new can as above. Remember to shut off the low side valve at the manifold gauges between cans and when you are completed.  We don't want any refrigerant leaking out and we don't want any air in the system.

Turn on car, start engine, MAX A/C, full fan, windows open.

Charge remaining cans RIGHT SIDE UP!  Install your vent thermometer into the center most vent to monitor the temperature coming out of the vents as you are charging.  Keep adding refrigerant until you reach about 2.0 x ambient temperature (ambient temperature is the area temperature measured approximately 6 inches in front of the condenser) on the high side gauge.  (i.e. 90*F outside would mean 90 x 2.0 = 180 PSI)  Keep a close eye on the low side gauge while charging as well.  You should end up with 25 to 40 PSI on the low when the vehicle is fully charged.  Low side gauges are good for monitoring any abnormal pressure readings (too high or too low) during a charge so you can stop at any time and correct the problem.  You should charge while the engine is at 2000 RPM.  This is where the diagnostic RPM gauge can come in handy as there is no guess work when revving the engine as the gauge sits there in front of you in the engine compartment.

Good charge should be 2.2 to 2.5 x ambient temperature.  For example:  If it's 90*F outside, a good pressure reading would be around 198 to 225 PSI @ 2000 RPM.  But use only as a guide.  Follow the instructions below to "fine tune" your charge.

Fine tuning involves adding enough refrigerant to hit around 2.0 x ambient temperature, then monitor the temperature gauge at the vents.  Add enough to go 5 more PSI on the high side, record the temps at the vent.  Keep doing this until you either notice the temperature start to get higher or you reach 2.5 x ambient temperature on the high side pressure gauge.  If you notice the vent temperatures start to increase, you may evacuate the small amount added to reduce the temperature again or simply stop.  If you hit 2.5 x ambient temperature on the high side stop and check out our troubleshooting guide on possible causes.  Vent temps should be around 50*F to 55*F at idle.  I recently converted a 1992 Honda Accord and with Honda's AC systems being "not so great," I was able to achieve 51*F at the vent on MAX AC, 47*F at MAX AC, half fan.  When you get the best (lowest) vent reading while charging and you feel comfortable that you got the best temps, let the car run, close the windows, set the fan to half (or close to it) and wait 5 minutes.  Check the vent temps.  This is your base mark temps.  You may vary anywhere from 45*F to 55*F.  

While the AC is still on, disconnect the low side connector and install the valve cap.  Shut off engine or turn off AC and allow the pressure on the high side to drop to 100 to 110 PSI as the system is equalizing.  Remove the high side connector and install the high side valve cap.

Take it out for a test drive with the AC on.  With air blowing over the condenser providing better heat removal, you should notice the temps drop at the vent a few more degrees.  During the driving test, I got as low as 41*F to 42*F at the vent on MAX AC, half fan.

Fill out that label and place it where the old label was.  Ensure to fill out the refrigerant type, amount of refrigerant, oil type and amount of oil (most important). 

Click [Next] for Troubleshooting and Additional Tips
Or [Back] to return to the first page

Allan Reinike

If you would like to contribute your projects to IROCZone.com, e-mail us at info@iroczone.com!