pmihaltian

This winter I totally rebuilt my AC system. New condenser, drier, hoses, compressor. We were only able to get 1 can of R12 into it due to it not being hot enough outside to get a full charge into the system. The plan is to fully charge the system next month when it gets really hot outside. The system runs cool now and seems to work fine, but its not icy cold due to only having a partial charge in it.

My problem is that sometimes when I turn the system on and it starts to blow cool air, I hear a slight rumbling noise coming from the firewall area near the evaporator lines. I think this may be an AC relay, sensor or switch that is acting up. Any ideas of what this noise might be or what to look for or test? Any help will be appreciated.

surfer92

After you changed everything, did you vacuum out the system?

Did you put the required amount and type of oil?

pmihaltian

Yes, we put 3 oz of mineral oil in the compressor and 3 oz in the accumulator. Then we pulled a vacuum and let it sit for 1/2 hour to asure that there were no leaks. THEN we added 1 can od R12. That was all we could get it to take because it was cold out side.

SunCr

Hopefully it's not the compressor. It needs a full charge to carry the oil that lubes it. Oil capacity is also 8 ozs. I wouldn't use it until you finish charging. Simply jumpering the Low Pressure Switch will keep it running long enough to top it off. If it's below 60, you can keep the main fan off or not pull the fan switch harness allowing the cooling fan to cycle and that should keep icing to a minimum under borderline conditions. Once it's charged, start other diagnostics.

pmihaltian

Oh, I also added 2 oz. of oil to the condenser. It’s definitely not the compressor. It sounds like one of the switches. Maybe the low pressure switch. Would that make sense?

gaguy

Why did you change everything?
Why you didn't convert it to 134?
When you charge AC you have to get compressor running by shorting low pressure switch.

pmihaltian

Why did you change everything?

Because the compressor was shot and 40% of the condenser fins were bent or damaged AND the system leaked

Why you didn't convert it to 134?

I want to keep the car original for NCRS judging purposes


When you charge AC you have to get compressor running by shorting low pressure switch.

Yes, I know.

SunCr

I don't know of any reason for a switch to make noise. The usual cause is a faulty compressor or it's sending liquid slugs back to the compressor. The last new compressor I bought - from Autozone - was DOA. I didn't know it until I installed it and charged it up. They gave me another one plus the gas and oil I wasted.

SunCr

PS - if you rebuilt it because the compressor seized, hope you flushed it - I suppose metal that's gotten pass the orifice might rattle around inside of the Evaporator. Never seen it as every blowup I've dealt with didn't get pass the orifice screen, but I don't know enough about your rebuild or the shape it was in before you took it apart.

surfer92

I did have a car once that kind of made the sound you are talking about, one of the lines was not bolted down and the vibration could be heard in the cabin.

pmihaltian

The compressor did not blow up or seize. It leaked oil and would not hold a charge for long, but it would hold a charge for a few weeks or so before all or most of the gas leaked out. I sent the OEM compressor to Classic Auto Air in Tampa for rebuilding. Classic looked it over & said that the rear bearing as well as the front bearing was shot and, in their opinion, if was not worth attempting to rebuild. Soooooo. I found a NOS R4 compressor at a Chevy dealer in Mississippi. This new old stock compressor is what is installed.

We replaced the orifice tube as part of the rebuild. There was some very minor small metal flakes in the old orifice tube. The AC tech who helped me said that the flakes were very minor & not to worry about them.

All-in-all everything has been changed except the evaporator. As surfer92 says, it may be a hose or tube that is not clamped down tight enough. I'll check that out today or tomorrow. If thats not it, I'll just have to wait until next month when it heats up and we get the system completely charged up to do our final troubleshooting. I'll let you know what happens. More later....

PS - thank you all for your helpful insight.

samsonb

How much were they gonna charge for a rebuild?

pmihaltian

Not too much, Josh. As I recall it was going to be about $150 or so. They also refurbished my accumulator for about $80 and rebuilt a couple of hoses. I thought that they did a pretty good job, were easy to deal with and honest. Here is their contact information if you are interested:

Classic Auto Air Mfg.
4901 Rio Vista Avenue
Tampa, FL 33634 USA

_____________________________

Work: 813-251-2356
Fax: 813-254-7419
Main: 877.342.5526 ext 235
E-Mail: sales@classicautoair.com
Website: www.classicautoair.com

Note:
Factory A/C Parts & Services
Curtis = Shop Manager
Mark = A/C repair technicial

samsonb

Thanks. Mine may be more expensive. I have the Nippodenso one on my 89. Brand new they are $600. Rebuilt $400.

Mine works fine, but it just started slinging a little oil out the front seal.

pmihaltian

Call the guys at Classic Air and ask them the price to rebuild yours. You may be pleasantly surprised with the answer. Check it out...

jtc44

If charging using cans of R12 and it is cold out place can in a pan of warm water to help flow also shake the can up and down Just rember gas to low side and licuid to hi side also sys should allways be vaced. befor charging!

samsonb

I'll give them a call. It couldn't hurt. The only problem if I do this. I've got R12. That means converting to R134, which is fairly expensive to flush everything, new orifice, new orings, and new drier would be needed regardless. So, that tacks on an extra $150 or so.

And I'd have to find a good shop. A couple of the shops I called about converting to R134, they said they just put a vacuum on it, then fill with R134. Not good. I asked them why they didn't at least replace the drier, they said you don't need to and they've been doing it for 30 years. Haha. I guess when your system blows up later on, they can then charge you $1k to replace it all.

pmihaltian

Josh, you can rebuild your current compressor and refill the system with R12. You do not have to convert it to R134. If you stay with R12, then all you need to do is rebuild the compressor and refill it with Freon. Some folks say that you will need to replace the drier once you open the system up, but you can get a new one for about $50 or so.

samsonb

Yeah, but R12 is expensive and hard to find. Plus lots of shops don't deal with R12 since all their stuff is set up for R134.

A new drier and orifice is a must. Especially after rebuilding the compressor. Some places say you have to flush the system to get a warranty on their rebuilt compressor.

tonyponykay

my system is r12, i think my compressor is siezed up or else there isnt enough pressure to get the compressor running...

the compressor doesn't engage even with power to the connector...

not sure what is up...cause when i turn the ac off, there is still power to the connector to the compressor...but compressor is not moving..

87 convertible...

thanks
tk