Intermittent air conditioning problem (Altima '00)

[verytrue]

Hi. I have read articles here for the past few months but I recently joined.

I had intermittent air conditioning problem. Sometimes it blew cold air and other times only warm air. Then, after I went to the mechanic who couldn't find the problem, it completely gone dead.

So I took it to the dealer shop. They said it was ECM computer, so I replaced to the used one in the other shop. Then it worked intermittently again. But soon after, it's gone dead again. Having searched the internet, in many case the problem is on temperature control amplifier. So I asked to another mechanic to see if it works fine after changing it to new one but it didn't work for mine.

Again, I went to the dealer explaining my problem. They think it is ECM again, stating that the ground is not coming up from ECM for air conditioning.

My feeling is that ECM truly does not ground up for air conditioner. But the initial reason is wires or temperature control sensor. Either of them gave overhead to the ECM so that the ground part for air conditioner became malfunctioning. Probably, it intermittently worked because of the sensor and then the mechanic gave too much overhead by turning frequently on/off.

I am on my way of making a decision whether I need to install new ECM($1150), or ask them to look into the other possibilities such as disconnected wires. They said it will take 2.5 hours to completely look into the problem.

If any one has any opinion or the same experience or hopefully answer, I would greatly appreciate for sharing with me.

Thanks in advance.

[MaximA32]

Have they checked the charge on the a/c system?

[verytrue]

I should have mentioned this, but they performed every basic checkup(freon and etc..) they can do without the need of disassembling something for the air conditioner. I went to the 3 different mechanics. They spent about an hour on average, so they have not done the complete check-up needing disassembling.

[NM50]

The ECM does provide a ground to the A/C relay.Buying a service manual and grounding the pin at this relay will take the ECM out of the equation.The safety switches such as the pressure switch and thermistor will allow the compressor to disengage when needed.