AC Questions............What would you do?

Sunroof · 06-10-2008, 10:33 AM

Okay, my 1973.5T had the dealer factory installation that is 35 years old! Compressor was replaced about 8 years ago with an upgrade, as too the old red cloth barrier hoses replaced with new ones, all around. Add a new drier and R-134conversion and for an older 911 and it has made the difference between fainting in bumper to bumper Atlanta traffic to staying sane!! Does'nt freeze you to the bone, but those knee level vents sure does keep the torso and parts south happy!

Now that my high pressure fitting at the compressor broke and the R-134 is all gone (oil drips out the hose now and then), I am thinking it might be a good time to clean components or do some type of maintenance while I wait for new parts.

Someone recommended I vacuum the system, but can I reverse that and pump in compressed air instead and open a line, say at the front condensor to vent and clear out gunk? Can I just use compressed air in each component (take off the hoses and just blow?)

Does it pay to use those spray can cleansers to remove old caked on oil or gunk in the evaporator, expansion valve and the two condensers then blow out with compressed air?

MUST I replace the drier (one-year old) now that I have the system open and the R-134 is gone? Everytihng I read about AC says, REPLACE!!!

What would you guys recommend as for any maintenance in a situation like this?
I expect my AC system will be down for several weeks................the evaporator, expansion valve and front and rear condensors are all original.

Thanks

Bob
73.5T

tcar · 06-10-2008, 10:38 AM

Don't need to replace the drier if it's that new.

You DO need to have a vacuum pulled. you have to get the air out of the system before recharging or you're wasting your time.

DO NOT spray cleaner into the compressor.

schamp · 06-10-2008, 11:28 AM

If that dryer has been open to outside air for awhile I would change it. You could easily blow a new hose as a result of the dryer being bad. Not worth the risk of losing and having to replace not only the dryer but the freon as well.

tcar · 06-10-2008, 11:43 AM

Agree, had impression that it hadn't been open more than a day or two...

If it's been awhile in humid Georgia, replace.

tcar · 06-10-2008, 11:44 AM

Agree, had impression that it hadn't been open more than a day or two...

If it's been awhile in humid Georgia, replace.

The vacuum will (as it's supposed to) remove a lot of humid air, but ...

CROWSC · 06-10-2008, 02:50 PM

Do not apply compressed air to any component in an a/c system.
Compressed air has moisture in it and a drop of moisture the size of the head of an
ink pen can clog your expansion valve. Also any moisture is going to be absorbed by the refrigerant oil and you may have to drain any and all oil form the compresser, condenser and evaporator to get rid of the moisture. If you want to leak check the system, put a static charge of refrigerant in the system and check for leaks with dish soap and water sprayed
on to the suspected leaks with a regular hand held spray bottle. the more soap to water
mixture is advisable. (a static charge is refrigerant that is put into the system without the engine running). do not start the engine while leak checking, or until you have fully evacuated the system (vacuum pump down) and added a static charge.
A dryer that is filled with moisture will not make you blow a hose, it will cause the system to run in a vacuum, and the dryer will frost up when unit is operating.
Your worst enemies are moisture and air in an a/c system.
I was the service manager at Carrier Transport Refrigeration for 20 plus years, and now have my own business and am a Carrier A/c warranty and parts station for the past 16 years.

Sunroof · 06-11-2008, 04:12 AM

Thanks........

What would you recommend for cleaning out older components (evaporator, condenser, for example)? With hoses off can these be flushed, blown through with compressed air and allowed to dry?

Bob

ljowdy · 06-11-2008, 05:42 AM

I watched an AC repairman insert Nitrogen into the system (no moisture) and check for leaks. Once that was done, the system was evacuated and charged.

As an addition. I had dealer installed air on my 1973. I personally modifified the system using a new receiver/dryer, new evaporator, new compressor, new barrier hoses and a 3rd condenser located under the back left fender, new temperature controller and a new reostat for the fan which allowed infinite speeds when adjusting the blower fan.

Everything worked good but the absolute best addition was getting rid of the dealer vent system and buying a set of knee pads and the factory vents. The factory vent system not only looks better but it directs the air much better and with more force.

CROWSC · 06-11-2008, 05:56 AM

If you go to CAR QUEST or NAPA auto stores, they will have an a/c flush kit.
The only sure way to blow through the components would be with nitrogen, because it will
actually grab any moisture and take it out. If you know anyone who has an a/c repair shop,
they probably have nitrogen, if not, the nitrogen is cheap. But the gauges and hoses that go to the tank, are not. Not worth it for a one time shot. Just remember that when you flush the components, you are going to remove any refrigerant oil that has accumulated in these components and you will have to add enough oil to the system before recharging to compensate for the loss.
I really think that the flush will do it. You might remove the expansion valve and clean it out,
be careful not to damage the valve though, it is very fragile. I would also remove the condenser and plug off the open ends very well, and clean the coil. Dirt and bugs clog the condenser coil and dampen the air flow, which is vital. You can use high pressure water and soap to do this, maybe go to the carwash and do it.

billybek · billybek's Garage

The flush kit will also remove most of the old oil in the system (not a bad thing since oil for R134a has a high affinity for moisture). Once the system is cleaned up make sure the correct oil charge for the system is installed then the refrigerant charge.
If the system has been open for a while, make sure a vacuume has been pulled for a good looong time! +1 on drier replacement!

mthomas58 · 06-11-2008, 06:15 AM

Quote:

Originally Posted by Sunroof

Thanks........

What would you recommend for cleaning out older components (evaporator, condenser, for example)? With hoses off can these be flushed, blown through with compressed air and allowed to dry?

Bob

Bob, I'd recommend the "T-1000 flush gun". You're more than welcome to borrow it!

Worked great on my rear deck condenser. Its gravity fed/compressed air powered.

Mineral spirits is OK for metal components but use a commercial flushing agent like the one shown from Advance Auto for hoses as they may absorb the solvent and create contamination problems in your system.

bazar01 · bazar01's Garage

Quote:

Originally Posted by CROWSC

If you go to CAR QUEST or NAPA auto stores, they will have an a/c flush kit.
The only sure way to blow through the components would be with nitrogen, because it will
actually grab any moisture and take it out. If you know anyone who has an a/c repair shop,
they probably have nitrogen, if not, the nitrogen is cheap. But the gauges and hoses that go to the tank, are not. Not worth it for a one time shot. Just remember that when you flush the components, you are going to remove any refrigerant oil that has accumulated in these components and you will have to add enough oil to the system before recharging to compensate for the loss.
I really think that the flush will do it. You might remove the expansion valve and clean it out,
be careful not to damage the valve though, it is very fragile. I would also remove the condenser and plug off the open ends very well, and clean the coil. Dirt and bugs clog the condenser coil and dampen the air flow, which is vital. You can use high pressure water and soap to do this, maybe go to the carwash and do it.

Very good advise. I would only use nitrogen and flush solvent to clean out components. Nitrogen, small amount of refrigerant and electronic leak detector for leak testing. Soap and water for finding big leaks.

Sunroof · 06-11-2008, 08:24 AM

Thanks.......

Many options here............

Mark, that T-1000 looks interesting to say the least. I will assume, you pour the cleaner in the funnel at the top and its shot fairly quickly into the component and out into the receiving receptacle. No holding time? I just bought a nice compressor too!

What about those cleaners that are sprayed in via pressurized can and hose and the cleaner (MEK, xylene, etc) evaporates leaving no moisture? Are these worth a try?

Anyone else use that stuff?

Bob

mthomas58 · 06-11-2008, 09:50 AM

Quote:

Originally Posted by Sunroof

Thanks.......

Many options here............

Mark, that T-1000 looks interesting to say the least. I will assume, you pour the cleaner in the funnel at the top and its shot fairly quickly into the component and out into the receiving receptacle. No holding time? I just bought a nice compressor too!

What about those cleaners that are sprayed in via pressurized can and hose and the cleaner (MEK, xylene, etc) evaporates leaving no moisture? Are these worth a try?

Anyone else use that stuff?

Bob

Not enough pressure/life in those aresol products. Your need a min of 70-90 PSI and you should repeat both ways through the component until it flushes clear.

The T-1000 works great.......after all the time and effort designing and assembling it.......using it was somewhat of a dissapointment because is was over so quickly and now its parked in the attic

There is no substitute for the right tool for the job!

mthomas58 · 06-11-2008, 09:55 AM

Quote:

Originally Posted by Sunroof

Thanks.......

Many options here............

Mark, that T-1000 looks interesting to say the least. I will assume, you pour the cleaner in the funnel at the top and its shot fairly quickly into the component and out into the receiving receptacle. No holding time? I just bought a nice compressor too!

What about those cleaners that are sprayed in via pressurized can and hose and the cleaner (MEK, xylene, etc) evaporates leaving no moisture? Are these worth a try?

Anyone else use that stuff?

Bob

.....you'll get any residual moisture out of the system by pulling a vacuum on a good hot day.......and, as you know we've got alot of them around the corner here in Atlanta!

The flushing agent shown above contains some ester oil which stays in the component flushed and oil absorbs moisture when exposed to air......the vacuum pulls it out.

billybek · billybek's Garage

Quote:

Originally Posted by mthomas58

.....you'll get any residual moisture out of the system by pulling a vacuum on a good hot day.......and, as you know we've got alot of them around the corner here in Atlanta!

The flushing agent shown above contains some ester oil which stays in the component flushed and oil absorbs moisture when exposed to air......the vacuum pulls it out.

True for most mineral oils, but some of the synthetics will not release moisture even while under a deep vacuum.

If the system wasn't open for long don't sweat it (no pun intended) too much!!