Does anyone know what things the Engine ECU unit looks at that might affect the startup of the Air conditioner relay??

I chased the fault on my terracan back to the control line not going low to allow the A/C to startup.?

Has anyone got a list of ECU error codes?

This might help

Attached File(s)
 AC_Operation.doc ( 83k ) Number of downloads: 116

thnx but my unit is fully auto...I already have the manuals but nowhere does it give you indications of what the ecu looks at and what error codes will stop the compressor starting..

In case anyone needs to know...it is possible to bypass the engine ecu a/c control and use the A/C climate computer to control it.

Move the wire from the ecu compressor relay (it grounds the relay to turn it on) to climate control gnd terminal.

That way the climate control will operate the a/c through the triple switch (hi/low) and drop out the compressor relay as needed.

You lose some functionality (no ECU control) but the a/c works fine with all climate controls intact.

So does that mean that there really is a problem with your ECU not controlling the A/C correctly?

That or a wiring problem that will cost 3 days at $100/hr for an auto mechanic to find.... New ECU is $1600...both options are very expensive...

This all started after Hyundai started looking at a problem with the vent doors some time ago but I couldn't prove a thing.
They must have jarred some plug or connection because A/c started playing up after that !

Of course they don't want to know you after warrenty is over unless you pay through the nose and in the end they just outsource the problem plus their cut to an auto elect who will advise Hyundai what the problem is and hyundai will then decide the ECU needs replacing (it may be ok but they will replace it) or the car needs to be taken apart to find the wiring problem at my expense

No way am I changing the ECU unless other engine related problems are apparent.
Hyundai noted that they had never ordered an ecu for a terracan since the car was introduced! so odds are the problem is wiring related.

This post has been edited by pickard: Jan 24 2008, 06:57 AM

I would have to agree with your thoughts that there is not a problem with the ECU, but more likely in the wiring. There appears to be only three wires that go to the ECU which have an input from the A/C circuit. They are the only ones that would need to be checked. You could perhaps make up a jumper cable and test each wire individually (ie. use the jumper cable from the ECU to where ever it is connected the bypass the wiring loom). If by chance the problem goes away when one of the circuits is bypassed by the jumper then the problem has at least been localised.