Aircon fault finding

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LanzaroteSteve

New Member
Posts
48
Hi guys, I'm trying to work out why my a/c doesn't work on my 1988 3.5 EFI.
At the moment I have the dash off and have checked the a/c motor works by connecting this to the power connections for the heater motor so all good.
Hotwired the compressor clutch and this engages so that looks ok.
When I took a meter reading from the connections for the a/c motor I'm only getting approx 8v when selecting the a/c setting on the control panel.
I can only hear/feel one relay clicking when I turn the a/c but looking at the circuit diagram I think I should be having 3 relays clicking (A/C Heater relay, Fan Replay and compressor clutch relay.
Does anyone know how to test a relay is ok? Can this be done with a normal multi meter?
Thanks
Steve
 
I'm not an electrical expert but can anyone tell me from this wiring diagram if the a/c blower motor should work even if the other a/c components don't? Provided the relay, connections and cables to the motor are ok?
I'd be happy to get the a/c blowers alone to work at the mo but I'm only getting 8v at the motor connections.
any help in getting to the bottom of this will be greatly appreciated.
Cheers Steve
 

Attachments

  • 1988 RRC AC wiring diagram.pdf
    35.7 KB · Views: 166
Datatek, the garages on the island where I live are pretty basic! They may have the testing gear but doubt they have the correct gas for a 25 yr old truck. Think I may be on my own with this one!
Will look on Ebay and hopefully get the gas brought to me by a friend some time soon!
Oh to live in a normal place where (you don't need a/c or that) you can order stuff easily and it just arrives!! haha!
 
The blower motor will always work if all is good, the A/C is separately switched.
What type of gas in your A/C, R12 or has she been converted to R134a. If R12 PLEASE do not attempt to test pressures by yourself, A/C gas is not friendly and R12 is extremely bad for the environment.
Then just a stupid question, you can buy A/C gas on e-bay??? without a licence???
this does not sound right to me, but hey I don't know the law of your country, my point being please be carefull.
 
Thanks Rangy 35, I don't really like the idea of messing around with it unless I fully understand what I'm doing. I think she will be on the original R12 gas.
There are 2 separate blowers, one for the fresh air and a different one for the a/c. The fresh air blower works but when I switch to a/c the a/c blower (I think) should kick in regardless of the pressure in the rest of the system.
I am getting power to the blowers but only 8v which isn't enough to start the blowers.
I have my dash in bits at the moment so if I could resolve the motor issue then I could at least put the dash back together and work on the rest or get a garage to take a look.
I'd really like a second opinion on the wiring diagram I attached (incase I'm wrong). If anyone could take a look and confirm if the blowers should work without the compressor etc?
 
rangy35 said:
The blower motor will always work if all is good, the A/C is separately switched.
What type of gas in your A/C, R12 or has she been converted to R134a. If R12 PLEASE do not attempt to test pressures by yourself, A/C gas is not friendly and R12 is extremely bad for the environment.
Then just a stupid question, you can buy A/C gas on e-bay??? without a licence???
this does not sound right to me, but hey I don't know the law of your country, my point being please be carefull.
Click to expand...
Yes:)
 
Its the fresh air or the recirculation motor that will run depends what you select, the blowers will work the A/C is switched separately, the A/C wont kick in if the high pressure switch detects enough pressure, but only if you switch the A/C on.
At 8v the motor should turn just not at full speed, you either have a seized/stuck blower, at what setting is the fan speed set, now don't hold me to the specs/figures I am about to give its just for explaining the basics, fan speed one goes through two resistors so 12v in but 5v out to the blower turning slow, fan speed 2 goes through one resistor so 12v in but 8v out so a bit faster and fan speed three is full 12v to the blower running full speed.
 
rangy35 said:
Are you serious, that is amazing, in what country do you guys live, if you don't mind me asking, and you are allowed to work on A/C systems without a licence.
Click to expand...
You can buy aircon gas on Ebay or in accesory shops like Halfords,
It's illegal to discharge the gas to the atmosphere, however it's usually all gone when work is needed so not a problem:)
Recharging from a can is no more dangerous than blowing up a tyre.
I thought OZ was an easy going country, if you need a licence to work on aircon, sounds worse than Europe:eek:
 
Datatek said:
You can buy aircon gas on Ebay or in accesory shops like Halfords,
It's illegal to discharge the gas to the atmosphere, however it's usually all gone when work is needed so not a problem:)
Recharging from a can is no more dangerous than blowing up a tyre.
I thought OZ was an easy going country, if you need a licence to work on aircon, sounds worse than Europe:eek:
Click to expand...

It is illegal to work on a aircon without a license in OZ, cannot buy gas without a license, and cannot buy well you can buy gas on internet but wont be shipped or pass customs, so you wont see it ever.
I know filling the system is fairly safe but you should still know what you are doing, inflating tyres can kill you, seen this happen twice in my short life.
 
rangy35 said:
It is illegal to work on a aircon without a license in OZ, cannot buy gas without a license, and cannot buy well you can buy gas on internet but wont be shipped or pass customs, so you wont see it ever.
I know filling the system is fairly safe but you should still know what you are doing, inflating tyres can kill you, seen this happen twice in my short life.
Click to expand...
If blowing up tyres were that dangerous, looking at some of the muppets that drive cars, there would be hundreds of deaths every year.
Health and safety gone mad.
 
I recently had my 88 RR re-gassed and before doing so did some reading: Although it is feasible to recharge an old R12 system with R134A it is not ideal, R134A has much smaller molecules than R13 and can weep through the rubber hoses of R12 systems (apparently the hoses of R134A systems are lined with PTFE) and the oil used with
R134A is not suitable for the seals in R12 systems.

I discovered that there are at least two current gases which are compatible for use in R12 systems, R416A and R413A. You might also have to change the valves on the system as most installers only seem to have equipment that fits those used on R134A system. I also had a problem finding an installer who used the R12 compatible gases, the nearest I could find was 20 miles away and the next was 80.

All of the re-gassing kits I have seen contain R134A gas so, if you do use one of these, you will probably have to change the valves yourself as well.

Hope this helps.
 
Last edited:
dougc said:
I recently had my 88 RR re-gassed and before doing so did some reading: Although it is feasible to recharge an old R12 system with R134A it is not ideal, R134A has much smaller molecules than R13 and can weep through the rubber hoses of R12 systems (apparently the hoses of R134A systems are lined with PTFE) and the oil used with
R134A is not suitable for the seals in R12 systems.

I discovered that there are at least two current gases which are compatible for use in R12 systems, R416A and R413A. You might also have to change the valves on the system as most installers only seem to have equipment that fits those used on R134A system. I also had a problem finding an installer who used the R12 compatible gases, the nearest I could find was 20 miles away and the next was 80.

All of the re-gassing kits I have seen contain R134A gas so, if you do use one of these, you will probably have to change the valves yourself as well.

Hope this helps.
Click to expand...
+1 and you can get valve adapters:) I have also seen R12 compatable gas in cans on Ebay.
 
Thanks for all the info guys.
At the moment I'm trying to look for electrical problems with the system as I believe the a/c blower fan should work even if the compressor etc doesn't. I've connected the a/c fan to the heater fan and it works fine. I'm going to replay the relays and see what happens.
I'm also considering connecting the heater fan and the a/c together so that they would both operate together. Any thoughts on this would be greatly appreciated? I'm thinking that if I can get the a/c fixed then it would blow through all vents and not just the centre dash, also should push a bit more air on normal (non a/c) operation.
 
LanzaroteSteve said:
Thanks for all the info guys.
At the moment I'm trying to look for electrical problems with the system as I believe the a/c blower fan should work even if the compressor etc doesn't. I've connected the a/c fan to the heater fan and it works fine. I'm going to replay the relays and see what happens.
I'm also considering connecting the heater fan and the a/c together so that they would both operate together. Any thoughts on this would be greatly appreciated? I'm thinking that if I can get the a/c fixed then it would blow through all vents and not just the centre dash, also should push a bit more air on normal (non a/c) operation.
Click to expand...
Both on one relay might be too much, you need to make both relays operate together.
 
Ok so after a few months playing around with the A/C and replacing relays etc it's still not blowing cold!
As far as I can see everything is working as it should i.e. the compressor clutch is engaging and the fans are blowing but still no cold air.
I am assuming (please anyone correct me if I'm wrong) that as the clutch is engaging the pressure switch on the drier (enough pressure) and the thermostat switch must be ok.
Both fans are spinning on the condenser.
I've felt the pipes from the compressor and one is quite hot and the other just warm (but not cold). The pipes into and out of the drier are both equal and just warm ish. The other end of the hot pipe coming from the compressor to the condenser is nowhere near as hot. Could this be a blockage in this pipe?
If anyone on here knows or has this model I'd really appreciate some advice as I don't want to start changing pipes and draining the system unless I need to?
 
LanzaroteSteve said:
Ok so after a few months playing around with the A/C and replacing relays etc it's still not blowing cold!
As far as I can see everything is working as it should i.e. the compressor clutch is engaging and the fans are blowing but still no cold air.
I am assuming (please anyone correct me if I'm wrong) that as the clutch is engaging the pressure switch on the drier (enough pressure) and the thermostat switch must be ok.
Both fans are spinning on the condenser.
I've felt the pipes from the compressor and one is quite hot and the other just warm (but not cold). The pipes into and out of the drier are both equal and just warm ish. The other end of the hot pipe coming from the compressor to the condenser is nowhere near as hot. Could this be a blockage in this pipe?
If anyone on here knows or has this model I'd really appreciate some advice as I don't want to start changing pipes and draining the system unless I need to?
Click to expand...

It's low on gas.
 
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