Air Conditioning
Discussion
I am looking for some advice. The air conditioning in my TVR has just been recommissioned and is holding pressure fine but it only blows really cold for a short period, say 5 to 10 mins and then warms slightly for quite a while and then cools down a bit and continues like that unless you switch it off. If switched off for a bit and then on again it starts the cycle again.
The question is how do I get it cold all the time? Is it likely overfilled or underfilled. The only air conditioning specific tools I have is the top up set from Halfords so rudimentary at best.
The car is a TVR Cerbera and before the condenser getting holed a while ago it blew properly cold, now repaired but not as good as it was.
The question is how do I get it cold all the time? Is it likely overfilled or underfilled. The only air conditioning specific tools I have is the top up set from Halfords so rudimentary at best.
The car is a TVR Cerbera and before the condenser getting holed a while ago it blew properly cold, now repaired but not as good as it was.
A Pro recharged the system.
Just checked the system with my top up kit and it is low on gas so I assume a leak somewhere. It passes the vacuum test but as that is a poor way of testing a pressure system I will get it tested with nitrogen and see if a leak can be found and stopped and then get it filled again.
Just checked the system with my top up kit and it is low on gas so I assume a leak somewhere. It passes the vacuum test but as that is a poor way of testing a pressure system I will get it tested with nitrogen and see if a leak can be found and stopped and then get it filled again.
Newer cars use R1234yf but ours still use R134a. You can't put the newer gas in a system designed for R134a.
Gruffalo, have you checked out whether the medium pressure switch in the trinary switch fitted to the drier is functioning? I've just been diagnosing some odd ac issues in my Tuscan. On the motorway ac performance was great but when queuing in town it was useless, although I could hear the compressor cutting in and out.
The pins in the conector to the trinary switch of my Tuscan were corroded and whilst there was a connection to the high & low switches, so the compressor would run, the medium pressure switch connections werent made anymore. The medium pressure switch turns 1 of the radiator fans on when pressure starts to rise to get some heat out of the condensor, maintaining the system pressure within normal running limits. Obviously what was happening in my case was the compressor would start and run until the high pressure switch tripped so there'd be a bit of cold air then nothing, then a bit more when the system had cooled. No problem on the motorway with a constant 70mph worth of air doing the cooling.
My Cerb has an Emerald ECU and thats set to run 1 fan all the time when the ac is on. I know you've got Dom's MBE so maybe that does something similar in which case it can't be the above.
Gruffalo, have you checked out whether the medium pressure switch in the trinary switch fitted to the drier is functioning? I've just been diagnosing some odd ac issues in my Tuscan. On the motorway ac performance was great but when queuing in town it was useless, although I could hear the compressor cutting in and out.
The pins in the conector to the trinary switch of my Tuscan were corroded and whilst there was a connection to the high & low switches, so the compressor would run, the medium pressure switch connections werent made anymore. The medium pressure switch turns 1 of the radiator fans on when pressure starts to rise to get some heat out of the condensor, maintaining the system pressure within normal running limits. Obviously what was happening in my case was the compressor would start and run until the high pressure switch tripped so there'd be a bit of cold air then nothing, then a bit more when the system had cooled. No problem on the motorway with a constant 70mph worth of air doing the cooling.
My Cerb has an Emerald ECU and thats set to run 1 fan all the time when the ac is on. I know you've got Dom's MBE so maybe that does something similar in which case it can't be the above.
CerbWill said:
Newer cars use R1234yf but ours still use R134a. You can't put the newer gas in a system designed for R134a.
Gruffalo, have you checked out whether the medium pressure switch in the trinary switch fitted to the drier is functioning? I've just been diagnosing some odd ac issues in my Tuscan. On the motorway ac performance was great but when queuing in town it was useless, although I could hear the compressor cutting in and out.
The pins in the conector to the trinary switch of my Tuscan were corroded and whilst there was a connection to the high & low switches, so the compressor would run, the medium pressure switch connections werent made anymore. The medium pressure switch turns 1 of the radiator fans on when pressure starts to rise to get some heat out of the condensor, maintaining the system pressure within normal running limits. Obviously what was happening in my case was the compressor would start and run until the high pressure switch tripped so there'd be a bit of cold air then nothing, then a bit more when the system had cooled. No problem on the motorway with a constant 70mph worth of air doing the cooling.
My Cerb has an Emerald ECU and thats set to run 1 fan all the time when the ac is on. I know you've got Dom's MBE so maybe that does something similar in which case it can't be the above.
Hi Will,Gruffalo, have you checked out whether the medium pressure switch in the trinary switch fitted to the drier is functioning? I've just been diagnosing some odd ac issues in my Tuscan. On the motorway ac performance was great but when queuing in town it was useless, although I could hear the compressor cutting in and out.
The pins in the conector to the trinary switch of my Tuscan were corroded and whilst there was a connection to the high & low switches, so the compressor would run, the medium pressure switch connections werent made anymore. The medium pressure switch turns 1 of the radiator fans on when pressure starts to rise to get some heat out of the condensor, maintaining the system pressure within normal running limits. Obviously what was happening in my case was the compressor would start and run until the high pressure switch tripped so there'd be a bit of cold air then nothing, then a bit more when the system had cooled. No problem on the motorway with a constant 70mph worth of air doing the cooling.
My Cerb has an Emerald ECU and thats set to run 1 fan all the time when the ac is on. I know you've got Dom's MBE so maybe that does something similar in which case it can't be the above.
the system has been fully checked over and I seem to have a leak. When topped up it works perfectly for a bit and then slowly gets worse as it loses gas.
It hold a vacuum well but that is a crap test for AC as the system operates under pressue not vacuum and the max you can get with a vacuum is 14.7PSI differential anyway.
The receiver dryer and Trinary switch are new so I have it booked in for a pressure and sniffer test next week, hopefully that will show up an bad "O" ring or something that needs replacing and not a holed heat exchanger in the wing.
The AC thermostat is under the dash, above your right knee. If it’s set too cold the AC cycles like you describe. The evaporator ices up, the AC shuts down until it melts and clears, then rinse and repeat. Common Cerbera AC problem.
Can’t remember which way you turn the stat though, Mr Google can probably help with that.
Can’t remember which way you turn the stat though, Mr Google can probably help with that.
fatjon said:
The AC thermostat is under the dash, above your right knee. If it’s set too cold the AC cycles like you describe. The evaporator ices up, the AC shuts down until it melts and clears, then rinse and repeat. Common Cerbera AC problem.
Can’t remember which way you turn the stat though, Mr Google can probably help with that.
Thank for this but I am 100% losing gas from the AC so have a proper pressure test booked for Monday.Can’t remember which way you turn the stat though, Mr Google can probably help with that.
I just hope it is an easy fix.
Well that was a waste of time, the company that said they could do a proper professional pressure test put the car on the ramps had a glance over the AC pipes and said they couldn't see any leaks as not green dye evident so gave up.
I guess the next step is to take the panel off of the drivers wing and look for signs of a leak and green dye in there.
I guess the next step is to take the panel off of the drivers wing and look for signs of a leak and green dye in there.
Hello Gruffalo,
I might be able to help, depending on how far away you are from me. I've rebuilt/recommissioned Cerbera air conditioning systems and I think I still have everything required, o rings, liquid PTFE, oil, refrigerant and the compressor and the manifolds needed.
Couple of thoughts...
Looking for indicator dye might be useful, assuming that some was added to the system the last time it was services/recharged. If no dye was added, looking for it won't be helpful. Also, if the slow leak is on the back of the condenser, it will be very hard to see without removing the radiator, which I hope isn't the case.
Drawing a vacuum (-30psi) on both A/C circuits is very important for two reasons. Drawing -30psi for at least half an hour evacuates the atmosphere and any moisture from the system. Once this is done, lock off the vacuum and leave for an hour to make sure that no leaks exist. If the manifold gauges are is still showing -30psi, connect the refrigerant to the manifold, purge any oxygen from the line and you'll be ready to start charging the system. See pictures attached,
The usual cause of the issues I have seen are due to a leak in the A/C condenser as this is vulnerable to stones and debris entering through the vents in the front of the car and piercing it.
I'm hoping in your case that checking each connection first and replacing the o rings (moistened with A/C oil) and carefully reassembling (to avoid pinching the o rings) and sealing with liquid PTFE will resolve your slow leak. I absolutely think you should start here, while keeping a lookout for any indicator dye.
Don't forget to remove the passenger side wheel and wheel arch inspection panel, where you'll find the dryer (attached to the panel) and trinary switch (fitted to the dryer). inspect for leaks and reassemble with o rings and liquor PTFE as above.
Happy to help if you need anything, let me know.
Best regards
Tony
![](https://thumbsnap.com/sc/aqWNy7Ys.png[/img]</a> <a href="https://thumbsnap.com/BGTbsq1U" Target="_blank" rel="nofollow">[img]https://thumbsnap.com/sc/BGTbsq1U.png)
I might be able to help, depending on how far away you are from me. I've rebuilt/recommissioned Cerbera air conditioning systems and I think I still have everything required, o rings, liquid PTFE, oil, refrigerant and the compressor and the manifolds needed.
Couple of thoughts...
Looking for indicator dye might be useful, assuming that some was added to the system the last time it was services/recharged. If no dye was added, looking for it won't be helpful. Also, if the slow leak is on the back of the condenser, it will be very hard to see without removing the radiator, which I hope isn't the case.
Drawing a vacuum (-30psi) on both A/C circuits is very important for two reasons. Drawing -30psi for at least half an hour evacuates the atmosphere and any moisture from the system. Once this is done, lock off the vacuum and leave for an hour to make sure that no leaks exist. If the manifold gauges are is still showing -30psi, connect the refrigerant to the manifold, purge any oxygen from the line and you'll be ready to start charging the system. See pictures attached,
The usual cause of the issues I have seen are due to a leak in the A/C condenser as this is vulnerable to stones and debris entering through the vents in the front of the car and piercing it.
I'm hoping in your case that checking each connection first and replacing the o rings (moistened with A/C oil) and carefully reassembling (to avoid pinching the o rings) and sealing with liquid PTFE will resolve your slow leak. I absolutely think you should start here, while keeping a lookout for any indicator dye.
Don't forget to remove the passenger side wheel and wheel arch inspection panel, where you'll find the dryer (attached to the panel) and trinary switch (fitted to the dryer). inspect for leaks and reassemble with o rings and liquor PTFE as above.
Happy to help if you need anything, let me know.
Best regards
Tony
I've not read through all the posts but a couple of things could do that.
Pressures - If the pressure is too high or too low, it could cut the compressor off
Evaporator freezing - Can be caused by moisture in the system hence causing a block
Expansion valve - Can get blocked and cause a block
Heater valve - If vacuum operated, can open due to a leak and let in hot air
If you turn off the air condition for a few minutes and then turn it on again. If it works fine for a while and stops, it's going to be one of the top three on my lest. Put gauges on it and you'll find out
Pressures - If the pressure is too high or too low, it could cut the compressor off
Evaporator freezing - Can be caused by moisture in the system hence causing a block
Expansion valve - Can get blocked and cause a block
Heater valve - If vacuum operated, can open due to a leak and let in hot air
If you turn off the air condition for a few minutes and then turn it on again. If it works fine for a while and stops, it's going to be one of the top three on my lest. Put gauges on it and you'll find out
Tony69 said:
Hello Gruffalo,
I might be able to help, depending on how far away you are from me. I've rebuilt/recommissioned Cerbera air conditioning systems and I think I still have everything required, o rings, liquid PTFE, oil, refrigerant and the compressor and the manifolds needed.
Couple of thoughts...
Looking for indicator dye might be useful, assuming that some was added to the system the last time it was services/recharged. If no dye was added, looking for it won't be helpful. Also, if the slow leak is on the back of the condenser, it will be very hard to see without removing the radiator, which I hope isn't the case.
Drawing a vacuum (-30psi) on both A/C circuits is very important for two reasons. Drawing -30psi for at least half an hour evacuates the atmosphere and any moisture from the system. Once this is done, lock off the vacuum and leave for an hour to make sure that no leaks exist. If the manifold gauges are is still showing -30psi, connect the refrigerant to the manifold, purge any oxygen from the line and you'll be ready to start charging the system. See pictures attached,
The usual cause of the issues I have seen are due to a leak in the A/C condenser as this is vulnerable to stones and debris entering through the vents in the front of the car and piercing it.
I'm hoping in your case that checking each connection first and replacing the o rings (moistened with A/C oil) and carefully reassembling (to avoid pinching the o rings) and sealing with liquid PTFE will resolve your slow leak. I absolutely think you should start here, while keeping a lookout for any indicator dye.
Don't forget to remove the passenger side wheel and wheel arch inspection panel, where you'll find the dryer (attached to the panel) and trinary switch (fitted to the dryer). inspect for leaks and reassemble with o rings and liquor PTFE as above.
Happy to help if you need anything, let me know.
Best regards
Tony
Hi Tony, you have a mail heading your way.I might be able to help, depending on how far away you are from me. I've rebuilt/recommissioned Cerbera air conditioning systems and I think I still have everything required, o rings, liquid PTFE, oil, refrigerant and the compressor and the manifolds needed.
Couple of thoughts...
Looking for indicator dye might be useful, assuming that some was added to the system the last time it was services/recharged. If no dye was added, looking for it won't be helpful. Also, if the slow leak is on the back of the condenser, it will be very hard to see without removing the radiator, which I hope isn't the case.
Drawing a vacuum (-30psi) on both A/C circuits is very important for two reasons. Drawing -30psi for at least half an hour evacuates the atmosphere and any moisture from the system. Once this is done, lock off the vacuum and leave for an hour to make sure that no leaks exist. If the manifold gauges are is still showing -30psi, connect the refrigerant to the manifold, purge any oxygen from the line and you'll be ready to start charging the system. See pictures attached,
The usual cause of the issues I have seen are due to a leak in the A/C condenser as this is vulnerable to stones and debris entering through the vents in the front of the car and piercing it.
I'm hoping in your case that checking each connection first and replacing the o rings (moistened with A/C oil) and carefully reassembling (to avoid pinching the o rings) and sealing with liquid PTFE will resolve your slow leak. I absolutely think you should start here, while keeping a lookout for any indicator dye.
Don't forget to remove the passenger side wheel and wheel arch inspection panel, where you'll find the dryer (attached to the panel) and trinary switch (fitted to the dryer). inspect for leaks and reassemble with o rings and liquor PTFE as above.
Happy to help if you need anything, let me know.
Best regards
Tony
Cheers
Martin.
Gassing Station | Cerbera | Top of Page | What's New | My Stuff