I know trad rods shouldn't have A/C, but can I go O/T for a minute to ask for some advice? I have a "Maxi-cooler II" in my car - it is aftermarket, I don't even know who makes it. The cold air quit last fall. It was working perfect one day, then just warm air the next time I started up the car a few hours later. This made me think the problem was electrical. I checked and found that the A/C clutch is engaging correctly, the fan is blowing, the heater valve is closed and the vent doors are working right. That would suggest a freon charge problem. The strange thing is that the cooling performance didn't gradually deteriorate like a slow leak and I didn't get a sudden release like a hose failure that would cause instant loss of cooling. Before I go to the local shop and fork over the $$ for a leak test/recharge, etc, is there anything I'm missing?
if the clutch is engaging then it doesnt sound like your having a charge issue. if it was empty then it wouldnt catch. probably something else.
Assuming you have a low pressure switch in the system then there is enough freon in the system to engage the clutch, if it is an expansion valve system it could be a hung valve, you can guess all day long, if you dont have a set of gauges borrow a set and look at pressures, if the valve is hung you will see the high side pressure very high and the low side suck down negative. You can try TAPPING on the valve, if it is orifice system then it is a different problem.hard to diagnose without some pressure readings
Since the clutch engages, there must be some charge left. You are only guessing until you check the pressures. If you can't borrow some gauges you will have to take it to a shop
Typically there is a low pressure switch in the system that will stop or cycle the compressor if the charge is lost or low. With the cooling on max and the fan running on high does the compressor clutch cylce or stay on? If it cylces and you have a low pressure switch then its probably low. The low pressure switch would be in a line or the dryer, typically on the passenger side by the heater/evap box. If the compressor does not cycle and there is a low pressure swith in the system and you checked everything you said then the compressor may have broke internally. When you turn the compressor on see if the engine idle drops as if there is a slight load applied. You can also check the two lines leaving the compressor, one should be hot and the other cold or cool.
I agree with bl moore adding, just because you have a LP switch doesnt mean its working correctly.... Its tough to diagnose with out guages reading high and low side.... Could be a plugged inline filter,,, pluged dryer??? The system needs to be sucked down, in hot climates about every 5 years....(Southern states), so you can guess with your usage, in your climate and how long its been since serviced.... A suck down and charge is only $75...
While you a/c experts are here, I've got a question. I just heard you could use/mix 134 refergerant in a R-12 system. The different a/c oils are the only reason we've been told they are incompatable. Also, r-134 is being "phased out" in the same way r-12 dissapeared, but the new stuff will be compatable in both r-12 and 134_a systems. Does anybody know the real story or have a link to more information?
You cannot retrofit 134a into an R12 system...the molecule of the R134a gas is smaller than the R12 molecules ....Automotive AC systems tend to leak at best from the shaft seal on the compressor, ...the R134a leaks for fun.The joints on the R134a systems were redesigned to cope with the "new" gas and employ "o" ring seals and different charging ports.R134a is also being phased out for another refrigerant. I used to carry just three cylinders of gas in my van,R12,R22 and R502...I now carry 10 different kinds and still come across stuff that I`ve never seen before..the job has been turned upside down with all this climate change crap. As for the original post...make sure the clutch is actually engaging...sometimes it looks like it is, just because the pulley is turning, .....if it is actually engaging for sure, it could be that your compressor is not pumping due to broken reeds or in some cases a bypass valve having opened and not reseated properly...this would give you enough pressure to keep the compressor relay energised by the L.P. switch, but have little or no refrigeration taking place.
find a friend to fix it , thats how i do it , did the last one at stray cat at dewey!! must be low again wont work up north but go south and the pressure goes up and then it works, honest it did that on the Iowa trip!!! and was running 50 degrees in the outlets felt OK to us !!!
simple test, if the low side line (bigger one) is cold and sweating the refrigeration part is working, you have an air control problem. if the low side is hot you need some gauges to see whats up
Maxi Cooler is made by Southern Air, http://www.southernrods.com/categor...-kits-southern-air/products/product-1978.html Try giving them a call.
why would the system need to be sucked down every 5 years? I have systems that are 15 and 20 years old have never been sucked down after initial suckdown , a good tight system may need a shot of freon every few years but thats about it, Texas is a pretty hot place.
If you don't have a leak, and everything is in good working order they will run indefinitely, climate makes no difference at all, as you have already observed. Sometimes the answers given on this forum are great, sometimes I have to bite my tongue to keep from correcting some of them.
Even though it is a sealed system, theoreticaly no contaminents can get in. True... only partialy... The compressor has many moving parts internaly along with oil for lubrication. Internals wear with friction and small particles make there way throuout the system... clogging over time small passages.. 1 place is the receiver dryer...There are variations of receiver-driers and several different desiccant materials used to remove moisture and other contaminants.... 2 Then the Accumulators....Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into the evaporator. It is connected directly to the evaporator outlet and stores excess liquid refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage. Compressors are designed to compress gas not liquid. The chief role of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is a good idea to replace the accumulator each time the system is opened up for repair and anytime moisture and/or debris is of concern. ( hot climate) Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant and forms a corrosive acid. When in doubt, it may be to your advantage to change the Accumulator or receiver in your system. While this may be a temporary discomfort for your wallet, it is of long term benefit to your air conditioning system. Vacuuming down your system and holding it removes moisture, ( boils it out) and with out moisture the corrosision process cant start, when parts carode, this also adds contaminants to the sealed system....
The bottom line here is ,you can't really tell what may be wrong without putting a set of guages on the system. Borrow some guages or take it in.
sorry, i've never heard of it being necessary to evacuate and recharge a/c systems every five years. i suppose theoretically this may be best pratice, but i have never heard this as a recommendation. at least in the automotive industry.
Heater control valve. Check it's function. The valve needs to be installed on the line from your intake manifold and not in the line to your water pump. Make sure it is plumbed for the correct direction of flow. Water flows from your intake-through the core-to the water pump. You can go to extremes and install a shut off valve in the suction (water pump side) line. These monolithic core systems are very responsive to heat.
Did auto AC for many years and I will try to help. First things first: 1.) Your AC clutch engages - for how long does it engage? 10 seconds, 20 seconds, 30 seconds, or just engages and stays on. 2.) Do you have an electric cooling fan or mechanical. If it is electric, it must be on unless you have a trinary switch on your AC unit. If it is mechanical, go to next step. 3.) I am assuming that your clutch/compressor are engaged. Go to the inside of your car - is the blower motor working? The switching mechanism on these newer all-in-one rod AC units work with a trinary switch that turn on the compressor, blower motor and electric fan (if this applies) all at once. If the blower motor is on and air is blowing out of the vents, start tracking the low side lines (smaller of the two -going into AC unit) and feel the temp. If it is cool but not cold it is probably low on refrigerant, hard to tell at this point without gauges. If it is cold, follow this to the inside of the car and see if this line is cool at the evap unit. 4.) If this is cold to the evap unit you are actually in luck. Check to see that you have not sucked up a piece of paper, or the like, and blocking the intake air of the unit. This is more common than you think and a very likely occurrence when you hear from a customer "it was working perfectly yesterday". 5.) I would need answers to the above before and I can tell you what to do next. Hope this helps.
Really? I must have been imagining the HUNDREDS of R12 systems that I've professionally converted to R134A over the years. A prime example of one would be my personal truck I converted over 10 years ago. It's an old 1968 Chevy. It still has all of the parts the truck came with from the factory ...and it still blows cold. ...You CAN convert a R12 system to R134A with success. Now the following isn't an end-all be-all statement, but most times you only need the correct oil and the adapter fittings for the service ports. Evacuate the system, add the correct retrofit oil and calulate the correct charge amount (typically 10% less than what the R12 charge would have been). Some systems need an orifice replacment, but it's not completely necessary with most systems ...the old orifice will work fine. The R12 system is more prone to leaks when using R134A, however if the seals are in good serviceable condition, and the guy doing the conversion knows his stuff, the converted systems work well. If the seals / hoses are not in good shape, simply replace them. Even if you did have to add an ounce or two every season for some reason, BIG DEAL. R134A is only around $18 a pound. You'll piss-off some tree-huggers ...but they can SUCK IT. To the OP, I'd be willing to bet your system is low on refrigerant.
I was wrong... service is 3 to 4 years.... Oops!! here is a good link to read for understanding the life and why... http://www.autoacsystems.com/_faqs/detail/compressor.html
I should have been clearer...you cannot just put R134a into an R12 system.....it requires new drier,hoses,shaft seal,charging ports,and any rubber seals need changing to neoprene..the oil needs removing from the compressor and the condenser and evaporator need flushing to remove all traces of mineral oil...I`d rather use a drop in like RS24 that requires no mods....up until recently we used R409 as a drop in replacement until that was phased out.
While I agree with most of this article, car nuts should not wait to "service" their AC systems until the 3rd or 4th year (unless the car was brand new). Anything older than this should be checked (and I mean checked only by an AC technician) every two years. A good AC technician will charge you a small fee ( $20 to 30 dollars) and have you wait while he does this. It should not involve putting on the gauges at all.
You are refering to a complete CONVERSION. A retrofit (which is the term I should have used) requires none of that in most cases.
Compressor stays engaged indefinitely. It will stay on as long as the A/C switches are on. Engine fan is mechanical. Air flow in and out of unit is not obstructed in any way. I will do the feel checks on the hose temps when I am back in the shop later this week. Thanks for the help.
So here's the scoop.... I put that gauges on and found zero pressure. Yup, no freon at all. I took the car to a good local A/C guy. He evacuated the system and it held 25 in vacuum for 10 minutes. Ho sign of a leak (so where did the charge go?). He charged the system up (1.75lb). With the car idling, pressures were 250high/15 low and 25 deg air temp drop from ambient. We tried more and less change and just couldn't get better balance on the pressures. So, we evacuated again, taking out some excess oil. with 1.55 lb of freon, pressures were 230/30 - a little better. Still 25 deg temp drop. We decided to leave it there. His guess is that the freon was lost from the blow off valve on the compressor (2000 Ford). Pressure probably got too high. My records show the original charge was 2.0 lb - maybe a bit too much. So, lessons learned: 1. Use a binary high pressure switch in the system to limit high side pressure. 2 Buy the good name brand A/C kit. Mine is a Chinese copy of the Southern Air unit and it seems that the component matching is not very good, hence the trouble getting a good pressure balance.
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