Airconditioner Cutting Off

[mackayboi]

Hi,
I hope this thread hasn't been started somewhere else... Admin please move it if need be.

This post relates to the GQ Nissan Patrol

For the past 3 months I was getting my air conditioner running nice and cold for about 5 minutes, and as soon as the engine heated up, the aircon would totally shut down, blowing hot air into an already hot day.

I found a solution but I am not sure the implications/problems this solution may bring.
I found a temperature regulator under the glove box with Two wires plus a copper? tube exiting a small silver box. I soldered a piece of wire between the two wires that attach to the regulator and this seems to prevent the air conditioner shutting down.

A fridgey told me that the only problem was the temperature gauge/valve for the aircon was broken and that is would cost me around 600 dollars to fix. due to the fact that to access the valve i need new regulation gas in the place of the original gas from pre-1994. I declined the quote, and found this solution.

Has anyone else done this modification?

Thanks.

[YNOT]

The regulator you are referring to is the A/C thermostat. The two wires coming out of it operate the clutch on the A/C compressor, and the copper tube (filled with gas) is placed in the air stream immedietly down stream of the evaporator. The thermostat tube senses the temperature of the air coming out of the evaporator which causes the gas in the tube to change pressure (expand and contract) which opens and closes a set of contacts inside the silver box.

The problem with what you have done permanently joining those two wires together, is that the compressor will now run continuosly which if everything else in the system is working properly (your fridgey seems to think it is) will cause the evaporator to freeze up. Running the compressor in this condition will damage the compressor.

Some thermostats have an adjusting screw on them allowing you to adjust the cut in/cut out point, this allows you to set them to cut out to about 1 degree (at the evaporator) which usually equates to 4 or 5 degrees at the vent. That's about the coldest you can run the A/C without causing freezing. Unfortunately not all thermostats are adjustable. Have a look at your thermostat to see if there is an adjustment screw as it sounds like your A/C is freezing up. If it is adjstable don't touch it just yet. Let me know and I'll run you through how to set it properly. The pic below shows an adjustable thermostat, the adjuster on yours may not be as obvious as shown here.

To replace the thermostat in most cases requires removal of the evaporator housing which is why your fridgey has told you the gas will need to be recovered. He is also correct telling you that pre 1994 vehicles were filled with R12 refrigerant (no good for the ozone layer apparently) which needs to be replaced with the more ozone friendly R134a. It's not a straight swap though, R134a is not compatible with the oil or O-rings used in R12 systems so they all need to be replaced. The filter dryer also needs to be replaced. Then the whole system needs to be evacuated down to remove all moisture from the system before it can be regassed. All this explains the high price on his quote.

Tony

[Bigrig]

The regulator you are referring to is the A/C thermostat. The two wires coming out of it operate the clutch on the A/C compressor, and the copper tube (filled with gas) is placed in the air stream immedietly down stream of the evaporator. The thermostat tube senses the temperature of the air coming out of the evaporator which causes the gas in the tube to change pressure (expand and contract) which opens and closes a set of contacts inside the silver box.

The problem with what you have done permanently joining those two wires together, is that the compressor will now run continuosly which if everything else in the system is working properly (your fridgey seems to think it is) will cause the evaporator to freeze up. Running the compressor in this condition will damage the compressor.

Some thermostats have an adjusting screw on them allowing you to adjust the cut in/cut out point, this allows you to set them to cut out to about 1 degree (at the evaporator) which usually equates to 4 or 5 degrees at the vent. That's about the coldest you can run the A/C without causing freezing. Unfortunately not all thermostats are adjustable. Have a look at your thermostat to see if there is an adjustment screw as it sounds like your A/C is freezing up. If it is adjstable don't touch it just yet. Let me know and I'll run you through how to set it properly. The pic below shows an adjustable thermostat, the adjuster on yours may not be as obvious as shown here.

To replace the thermostat in most cases requires removal of the evaporator housing which is why your fridgey has told you the gas will need to be recovered. He is also correct telling you that pre 1994 vehicles were filled with R12 refrigerant (no good for the ozone layer apparently) which needs to be replaced with the more ozone friendly R134a. It's not a straight swap though, R134a is not compatible with the oil or O-rings used in R12 systems so they all need to be replaced. The filter dryer also needs to be replaced. Then the whole system needs to be evacuated down to remove all moisture from the system before it can be regassed. All this explains the high price on his quote.

Tony

Mate - you should dead set organise to create something like "just ask" on the forum (have you seen that website?) - people ask the question and volunteer what it is worth to them - couple if dollars, ten dollars etc. If you answer and help them out (like you did for me), then they accept to transfer the money. Having met you, you are a top bloke and even if you didn't want to take the money (or at least all of it) it could be held by AB in trust as it were for the forum or something??? Places no pressure on you for an answer as you still pick and choose which ones you answer, but sees you/the forum rewarded for your input - I'd happily donate for what you have told me - you were about the only person who got the nail in the head first go and that was over the bloody phone!!!! Just a thought and yes I know there is always complications to be considered, but your input on this site is probably the reason many people have hung around.

Top job yet again old mate!!


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[starck]

I've had similar situation: AC started to go properly just after switching-on. But few minutes later intensity of cold air were falling down till zero.
Mechanic has solved the problem and while I asked about the reason he told me some feeler was too deep in .... whatever. Anyway this caused freezing of this feeler and freezing of the pipes that finally were not clear and stopped circulation.

Was enough to pull this feeler a bit out (few milimetres) and AC started to work again.
Hope my english was clear to understand the matter. If some of You could explain this better please do.

[YNOT]

Thanks Scott.

I see your point about it not being unreasonable to expect some reward either personally or for the forum for helping people, for me though I don't answer these questions for material reward, I do it because I like helping people. If it was me asking the questions I would be put off asking if there was an obligation to pay for it.

Tony

[YNOT]

I've had similar situation: AC started to go properly just after switching-on. But few minutes later intensity of cold air were falling down till zero.
Mechanic has solved the problem and while I asked about the reason he told me some feeler was too deep in .... whatever. Anyway this caused freezing of this feeler and freezing of the pipes that finally were not clear and stopped circulation.

Was enough to pull this feeler a bit out (few milimetres) and AC started to work again.
Hope my english was clear to understand the matter. If some of You could explain this better please do.

The feeler you are referring to is the thermostat tube and you are correct that if is not positioned correctly in the air stream it can cause freezing.

Tony

[Bigrig]

Thanks Scott.

I see your point about it not being unreasonable to expect some reward either personally or for the forum for helping people, for me though I don't answer these questions for material reward, I do it because I like helping people. If it was me asking the questions I would be put off asking if there was an obligation to pay for it.

Tony

Understood mate - didn't think you would do it for any other reason than to help, and that's the other thing - no one is obligated to pay, just volunteer that they would IF they had exhausted a few other avenues and if they felt it assisted the problem - no set amount, no obligation ... Like a donation as it were ... No drama either way, just feel guilty at times for all the assistance you've given me and others without ability to repay the favor in some fashion - I'm that sort of person I'm afraid, don't want handouts - free assistance is good, but as the forum continues to grow, your ability to 'meet the demand' (as it were) may get somewhat stretched ... That said, I'll populate your esky when we get out for the trip as my payment!!! Lol


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[Bigrig]

Sorry for the thread hijack mackayboi!!!


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[mackayboi]

Thank heaps YNOT, you sure are an asset to this wonderful forum. Thankyou.

Now I am concerned for my airconditioner compressor. (A lot better to have found out now, than find out when broken down)

So I guess I just need to adjust the red turning thingy as shown in picture?

All help is much appreciated.
Thanks for your previous in-depth explanation response.

[mackayboi]

What I am doing is enjoying the freezing cold air conditioner... and just turning it off after about 15 minutes to prevent over condensation.
Would turning off the A/C button turn the compressor off, thus defrost the evaporator.... ?

I am not too keen to spend money on something that works fine, because i can bear with the fact that I just manually control the air con.
Would like help if you got some to give YNOT, just message me.