Relay constantly clicking w/ A/C on

[thebird00]

Well the alternators are back on and the batteries are charged up. The truck is cranking strong and running good. A volt check at the batteries show 13.25 on the front battery and 13.8 on the rear. Hopefully this won't me a big deal. Maybe it's got to do with the flaming blue box.

I went to try the A/C out yesterday and it comes on fine, but the whole time it's running, the relay is constantly clicking. Is this normal? It blows cool, but not cold air. It may need some freon. Any ideas on the relay constantly clicking?

This is an M1010 ambulance for reference.

 

[Bill W]

Sound like its low on refrigerant which causes both cool air and the low pressure shutoff switch to kick on and off

 

[Blood_of_Tyrants]

It could also be overcharged with too much refrigerant. Get a gauge and check before you add.

 

[thebird00]

Re: RE: Relay constantly clicking w/ A/C on

It could also be overcharged with too much refrigerant. Get a gauge and check before you add.

Can the freon lose it's refrigeration, because the A/C doesn't seem to be cooling great, but that is with the truck idling and not moving.

 

[thebird00]

Is the the old R12 stuff in these units?

 

[Blood_of_Tyrants]

Re: RE: Relay constantly clicking w/ A/C on

It could also be overcharged with too much refrigerant. Get a gauge and check before you add.

Can the freon lose it's refrigeration, because the A/C doesn't seem to be cooling great, but that is with the truck idling and not moving.

No. Either not enough or too much refrigerant and it will cause the compressor clutch to come on and go off in short cycles. Too low and the low pressure switch kicks it off. Too much and the high pressure switch kicks it out to protect the system.

 

[thebird00]

I'm gonna put a set of gauges on it this morning. If it's low then I probably have a leak somewhere because the guy I bought it from claimed to have fixed the A/C last year. I wonder if I can even find R12 anymore. I surely do not want to spend the money to convert this thing.

He also claimed he had the alternators rebuilt.

 

[Blood_of_Tyrants]

It would be cheaper to convert it to R-134A than to charge it with R-22 (R-12 was for refrigerators and freezers) which can ONLY be gotten from a licensed shop. You can "rent" a vacuum pump from either Auto Zone or Advance Auto (I forget, but one of them will loan it for free if you place a deposit on it). The R-134A oil and refrigerant and charge fitting adapters will run less than $40.

 

[Crash_AF]

It would be cheaper to convert it to R-134A than to charge it with R-22 (R-12 was for refrigerators and freezers) which can ONLY be gotten from a licensed shop.

Umm, no... R12 was automotive and R22 was for residential/light commercial A/C and refrigerators/freezers...

You are correct that R12 is/was only available to licensed HVAC technicians and is hugely expensive now because production of new R12 ended in 1995. On the other hand, a licensed shop that still has R12 equipment will pay good money for any uncontaminated R12 left in your system which should cover part of the cost of the conversion to R134a.

Later,
Joe

 

[CCATLETT1984]

It would be cheaper to convert it to R-134A than to charge it with R-22 (R-12 was for refrigerators and freezers) which can ONLY be gotten from a licensed shop. You can "rent" a vacuum pump from either Auto Zone or Advance Auto (I forget, but one of them will loan it for free if you place a deposit on it). The R-134A oil and refrigerant and charge fitting adapters will run less than $40.

To convert you also must replace the rubber hoses in the AC system, otherwise the r134 will seep out the rubber.

 

[Crash_AF]

You don't have to replace the rubber hoses in the system to convert to R134a, only the O-rings on the fittings if you are concerned with their age. I've done several successful conversions over the last few years with no leakage issues, the oldest being a 1978 Bronco. The only parts I replaced in that system were the receiver drier and the O-rings due to age.

Later,
Joe

 

[thebird00]

Well I got the system checked. No freon at all. I found this stuff called freeze 12 that replaces R-12. It was 15 bucks a can. I think I may return it though and just go with 134a. This stuff is only about 5 bucks a can. I figure I have a leak somewhere so the 134a will be a cheap route to detect that.

Does anyone know how must the dye runs for leak checking? I have heard it's not cheap.

 

[CCATLETT1984]

you can get the refrigerant with the dye in it at the auto parts store, not that expensive. might be easier to have a shop leak test it though. I'd replace the dryer since they are cheap, and then pull a vacuum on the system and filler up

 

[CCATLETT1984]

You don't have to replace the rubber hoses in the system to convert to R134a, only the O-rings on the fittings if you are concerned with their age. I've done several successful conversions over the last few years with no leakage issues, the oldest being a 1978 Bronco. The only parts I replaced in that system were the receiver drier and the O-rings due to age.

Later,
Joe

REPLACING RUBBER HOSE LINES
is preferred for two keys reasons. First you must remember the "age" of the car. If you have an 1987 or older model year then your rubber AC lines are now over 21 years old! You most likely have replaced a few hot water coolant lines by now if you are prudent, and it does not make sense to have the system charged hoping they won't leak slowly over the season. Second, with the introduction of R134a came "barrier" hose line. Basically a hose within a hose that limits the probability that smaller R134a or even R12 molecules will slowly escape through the hose wall over time (why are you topping off the refrigerant every other year).