DIY A/C Repair

[joeysmith]

It's basically propane and flammable. To each their own.

New refergerant we had to switch to for home ac is now flammable

 

[The Old Codger]

A 1999 F-250 uses an orifice tube expansion device, and an accumulator to catch liquid refrigerant from the evaporator core for temporary storage in the HVAC system. Both of these should be replaced if the system has been devoid of refrigerant for any time. Orifice tubes have a screen filter and these plug over time as the compressor wears internally. Accumulators have a desiccant bed internal that absorbs moisture. The accumulator also holds excess oil that is "wicked up" by flowing refrigerant. Both should be replaced any time an HVAC system is opened for good measure.

As has been mentioned, a deep vacuum needs pulled on the system for a couple of hours to 29.975" on the gauge. This will boil off any residual refrigerant, and moisture in the system. The manifold valves are then closed, vacuum pump shut down, and dwell time started to ensure the system integrity. Myself, I then administer 50psi of nitrogen to the system allowing it to remain for an hour. If no loss in system pressure, then another vacuum is pulled and refrigerant is added along with an ounce of oil charge; (assuming system was just depleted, not ruptured).

When charging a system using a fixed orifice tube, use the superheat measurement to optimize charge level or quantity of refrigerant required. 13-17 degrees is good and is calculated during the recharging process. This is of course assuming clean coils, and adequate airflow across those coils. Allow the system to operate at least 15 minutes at about 1500 engine rpm to stabilize and continue to measure superheat adding finish charging as needed.

Rule of thumb on oil level for R-134A refrigerant is about 3.1 to 3.3 ounces of oil per pound of refrigerant in the system. Accumulator will hold a little excess but don't dump 10 ounces in the system or you'll "slug" the compressor taking the valves out. An ounce added to a depleted system won't hurt anything as a general rule. I generally use PAG46 myself with R-134A.

I only install parts I vendor and only for someone that is willing to bear the expense to repair the system correctly.

 

[joeysmith]

A 1999 F-250 uses an orifice tube expansion device, and an accumulator to catch liquid refrigerant from the evaporator core for temporary storage in the HVAC system. Both of these should be replaced if the system has been devoid of refrigerant for any time. Orifice tubes have a screen filter and these plug over time as the compressor wears internally. Accumulators have a desiccant bed internal that absorbs moisture. The accumulator also holds excess oil that is "wicked up" by flowing refrigerant. Both should be replaced any time an HVAC system is opened for good measure.

As has been mentioned, a deep vacuum needs pulled on the system for a couple of hours to 29.975" on the gauge. This will boil off any residual refrigerant, and moisture in the system. The manifold valves are then closed, vacuum pump shut down, and dwell time started to ensure the system integrity. Myself, I then administer 50psi of nitrogen to the system allowing it to remain for an hour. If no loss in system pressure, then another vacuum is pulled and refrigerant is added along with an ounce of oil charge; (assuming system was just depleted, not ruptured).

When charging a system using a fixed orifice tube, use the superheat measurement to optimize charge level or quantity of refrigerant required. 13-17 degrees is good and is calculated during the recharging process. This is of course assuming clean coils, and adequate airflow across those coils. Allow the system to operate at least 15 minutes at about 1500 engine rpm to stabilize and continue to measure superheat adding finish charging as needed.

Rule of thumb on oil level for R-134A refrigerant is about 3.1 to 3.3 ounces of oil per pound of refrigerant in the system. Accumulator will hold a little excess but don't dump 10 ounces in the system or you'll "slug" the compressor taking the valves out. An ounce added to a depleted system won't hurt anything as a general rule. I generally use PAG46 myself with R-134A.

I only install parts I vendor and only for someone that is willing to bear the expense to repair the system correctly.

Best was to do them is follow manufacturers numbers
Pretty easy to find online anymore
Will tell you exactly how much oil an refergerant the system requires
Superheat on an automotive system really is not an indicator of how the system is operating.
Especially with an accumulator in the mix

 

[The Old Codger]

One must do what works for them. If the end user is happy with the result, it's all good.

 

[chvet73]

People seem to think that AC is some kind of black magic. It's not rocket surgery and nothing to be afraid of. You can do the whole thing yourself with a couple extra basic tools and some information off the Internet, including the charging. OR you probably have someone in your area that does AC recharges out of their garage.

The only specialized equipment you need are a set of manifold gauges, which you can get from harbor freight, and a vacuum pump. You can purchase an inexpensive air-operated vacuum pump that runs off your shop air from Amazon for about $30. Pull a vacuum, add your oil charge, add refrigerant, done.

Barnyard is completely correct. I have my own pump and gauges. I have done several different cars and they all have been successful. My current project, 1970 Mustang Fastback has OldMan air kit that I put in.

 

[RedMF40]

A 1999 F-250 uses an orifice tube expansion device, and an accumulator to catch liquid refrigerant from the evaporator core for temporary storage in the HVAC system. Both of these should be replaced if the system has been devoid of refrigerant for any time. Orifice tubes have a screen filter and these plug over time as the compressor wears internally. Accumulators have a desiccant bed internal that absorbs moisture. The accumulator also holds excess oil that is "wicked up" by flowing refrigerant. Both should be replaced any time an HVAC system is opened for good measure.

As has been mentioned, a deep vacuum needs pulled on the system for a couple of hours to 29.975" on the gauge. This will boil off any residual refrigerant, and moisture in the system. The manifold valves are then closed, vacuum pump shut down, and dwell time started to ensure the system integrity. Myself, I then administer 50psi of nitrogen to the system allowing it to remain for an hour. If no loss in system pressure, then another vacuum is pulled and refrigerant is added along with an ounce of oil charge; (assuming system was just depleted, not ruptured).

When charging a system using a fixed orifice tube, use the superheat measurement to optimize charge level or quantity of refrigerant required. 13-17 degrees is good and is calculated during the recharging process. This is of course assuming clean coils, and adequate airflow across those coils. Allow the system to operate at least 15 minutes at about 1500 engine rpm to stabilize and continue to measure superheat adding finish charging as needed.

Rule of thumb on oil level for R-134A refrigerant is about 3.1 to 3.3 ounces of oil per pound of refrigerant in the system. Accumulator will hold a little excess but don't dump 10 ounces in the system or you'll "slug" the compressor taking the valves out. An ounce added to a depleted system won't hurt anything as a general rule. I generally use PAG46 myself with R-134A.

I only install parts I vendor and only for someone that is willing to bear the expense to repair the system correctly.

Thanks for the detailed information. Most of it went over my head but I do have a tenuous grasp of some of the concepts. In your opinion, how likely is it for a given shop to do all that?

 

[wore out]

New refergerant we had to switch to for home ac is now flammable

Yes it is!

 

[Hobo,NC]

Thanks for the detailed information. Most of it went over my head but I do have a tenuous grasp of some of the concepts. In your opinion, how likely is it for a given shop to do all that?

He left out balance the oil in the new compressor.

 

[Phill Tibbetts]

Would probably be best to line up the shop that's going to do the work before you pull the trigger. A lot of shops want to make money off the parts, too.

That's the name of the game, they buy the parts for a lot lesss than you can and then double the price to you.