QuestionQUESTION: Hi hope you can help. I have a range rover 4.6 hse brought from the UK to British Virgin Islands. Just when I need air con it does not work. Had it tested in garage here they said there was a leak. They cannot fix it so said I need a new condensore and evaperator, I have not got a clue. All the air blows out brilliant really strong especially hot but when I turned both sides down to the lowest it was still very warm not boiling but very warm. Please help.
ANSWER: Hi Teresa,
What year is your Range Rover?
It sounds like your blower motor is working just fine.
From the workshop manual:
If there is a build-up of dirt on the condenser unit fins, it could casue the condensor not to work properly resulting in poor cooling and higher operating temperatures. Also, make sure the air filter is not blocked. A blocked air filter will restrict
cooling of the evaporator and it is, therefore, important to renew both filters at the
recommended service schedule.
I'll try to clarify how your AC works and hopefully this will reduce your confusion.
I'll pull info from the workshop manual as a guide:
Refrigerant system
The refrigerant system comprises four major units:
• A compressor.
• A condenser.
• A receiver/ drier.
• An evaporator and thermostatic expansion valve.
The compressor
The compressor, a pump specially designed to raise the pressure of the refrigerant
(also called R134a), is mounted on the front of the engine. The compressor is driven via an electro-magnetic clutch by a single pulley drive belt that also serves the other engine ancillaries. (Compressor clutch allows pulley wheel to eiher be engaged or neutral and free spinning. The compressor has a pulley wheel that is turned by the serpentine belt that is 'driven' by the engine). Operation of the clutch is controlled by the ATC ECU (AC computer).
On vehicles up to 99MY, the compressor incorporates a thermal cutout switch in the electrical connection to the clutch.
The compressor draws vaporized refrigerant from the evaporator. It is compressed with a resulting rise in temperature and passed on to the condenser as a hot, high pressure vapour.
Condenser
The condenser is mounted directly in front of the radiator. It consists of a refrigerant coil mounted in a series of thin cooling fins to provide the maximum heat transfer. Air flow across the condenser is induced by vehicle movement and assisted by two electric fans attached to the frame of the condenser. The refrigerant high pressure vapour enters the condenser inlet midway on the LH side. As the vapour passes through the condenser coils the air flow, assisted by
the two fans, carries the latent heat away from the condenser. This induces a change of state resulting in the refrigerant condensing into a high pressure warm liquid. From the condenser, the refrigerant continues to the receiver/ drier.
Receiver/ Drier
This component acts as a reservoir and is used to hold extra refrigerant until it is needed by the evaporator. The drier within the receiver unit contains a filter and dessicant (drying material) which absorb moisture and prevent dessicant dust from being carried with the refrigerant into the system.
Evaporator and thermostatic expansion valve
High pressure liquid refrigerant is delivered to the thermostatic expansion valve which is the controlling device for the air conditioning system circuit. A severe pressure drop occurs across the valve and as the refrigerant flows through the evaporator it picks up heat from the ambient air, boils and vaporizes. As this change of state occurs, a large amount of latent heat is absorbed. The evaporator is therefore cooled and as a result heat is extracted from the air flowing across the evaporator. The refrigerant leaves the evaporator, on its way to the compressor, as a low pressure gas.
(If there is a refrigerant leak somewhere within these components, only heat will be blown into the cabin of your RR.)
If your mechanic suspects the condensor or the evaporator, or both, then you'll have to trust them. See if they can find parts to temporarily install and verify that indeed these are the components causing the problem. IF the compressor is not functioning, which is usually the case, you may end up buying all 3 of the 4 components described above. That's a very expensive repair as these parts are very expensive when purchased new.
I would imagine mechanics on your island know a lot about AC systems.
Unless you are a Do It Yourself mechanic, you are at the mercy of this mechanicc and
his expertise.
I hope this helps clarify things.
So to recap;
mechanics suspect refrigerant (R134a) is leaking from either the condensor or the evaporator, both are crucial components of the AC sysetem. Leaks are hard to find and it is suggested to replace rather than repair these components.
Best of luck with this repair,
JohnMc
---------- FOLLOW-UP ----------
QUESTION: Sorry John may I just ask if it is correct as machanic has told me they have to remove these which entails taking the dash board out and it could take upto 12 to take out and then 10 hours to put back. I really want to say dont be so stupid and stop messing me about but I cant unless you tell me? these are the worst rip off merchants you will ever come across I promise you. So I have to know what Im talking about. So far they quoted me around $3000.
AnswerHi Teresa,
the evaporator is located behind the dash in what is called the Heater assembly unit. IF they suspect the evaporator is faulty, they will have to disassemble the dash console to get to this. It's a long job and not one done lightly. If they are unfamiliar with disassembly, yes it could take that long - sorry to say. BUT if they are a shop that specializes in LR repair, then this is too long.
Is this Burkes Garage? They advertise that they sell and service LR's and report they have an experienced staff. If they are saying it will take 22 hours to remove and replace the evaporator, I'd be shocked. That's too long - twice the normal time.
As for $3000 quote, that's kind of high but I understand that costs will be higher for Island owners. A typical AC problem could be about $2000 here on the mainland, 3K$ is a complete rebuild of AC system. Evaporator is about $800 then there's the labour.
Do you have any other options? Is there another LR mechanic where you live to get a 2nd quote?
Regards,
JohnMc
