[snipboy]

I have a 2005 Touring model with 185k on it. AC was running like a champ until about 2 months ago. It was blowing warm air after a recharge which gave it 3 months of cold air. Mechanic diagnosed the issue as a faulty hose.

Now that the hose is replaced, about 15 minutes into running the AC, it abruptly stops blowing cold air. I can tell the compressor or condenser is kicking on and the MDX will shudder as if it knows there is an error in the system and shuts the compressor off. My mechanic once again took a look and said I had a dirty air inlet/condenser?? I am not sure what it is, but it sits in front of the radiator in the car. So, he hosed it down and almost immediately the car got cold again. He suggested I power wash it at a car wash. Just before arriving at the car wash, the AC started blowing warm again. The shuddering started. I left the car on while I power washed the front of the car and within a minute it was blowing ice cold air again and continued to for 15 minutes.

When the mechanic had the gauges hooked up to the AC system, he noticed a big pressure drop in the system after that 15 minute period would end. When you hit that front of the car with the water, the pressure lept up again.

He is baffled. What's going on here? Thanks!!

 

[Apex1]

Wait, so when did the problem start in relation to the last recharge?

When the tech noticed the drop in pressure, was it the high or low side? Or both?

It sounds like the system is contaminated or clogged. I am pretty sure its an orifice tube system, so you may need to replace the accumulator also.

 

[forbin404]

Or the tech messed it up when he replaced the hose.

 

[snipboy]

I am leaning towards the tech messing something up when he replaced the hose.

This problem started after the last recharge. It was on the low side. I took it to another shop to get a second opinion. They said they suspect that the compressor is going bad and that there might be debris in the system. They won't just replace the compressor, and quoted me 2300$ to do the full job: replace all hoses, condenser, compressor, piping, etc.

At this point, my MDX is only worth 2100 according to Edmunds. I was hoping to squeeze another 25k miles out of it. I have 185k on it now. The other mechanic is adamant that it's just the condenser and will refund me in total if it doesn't fix the problem. Guess I have nothing to lose.

 

[snipboy]

Plot thickens... the shop that gave me the 2300 quote said they were able to get a half hour out of the system after doing a vacuum flush and re-adding refrigerant. They said the last mechanic overfilled it just a little. Should be at .8 and it was at 1.0. Not entirely sure what that means or what it could mean for damaging the system.

Drove the MDX off the new mechanic's lot for about an hour and the air was still blowing cold. WTH. Is it possible the debris in the system, if there was any, cleared out somewhere? Also, I know this is a longshot, but I haven't replaced my cabin airfilter for years. Maybe five years. Could that be compounding my problem?

 

[forbin404]

Cabin Air filter is not related at all.
But wow, overfill eh? I guess you shouldn't go back to that mechanic eh?

 

[skirmich]

The system has a bypass for overcharging usually kicks in when the outside temp is too high and the condenser can't dissipate enough heat the system will shut off due to over pressure.

Try this: When the MDX stops putting cold air splash the front condenser with water using a hose if the MDX starts to put out cold air then your issue is with over pressure by pass only. If the compressor was failing it would not matter at all.

Solution is to properly fill the system to spec.
We get tons of issues with overfilling and over pressure here in south cali so it's quite normal to know this.

 

[snipboy]

Thanks Skirmich.

 

[forbin404]

Oh and the cabin filter takes about 10 minutes to change. You should do it.

 

[habbyguy]

You have to drop the entire glovebox out, and remove a small cross-member to change that filter, so it took me more than 10 minutes. Or maybe there's a shortcut? I'd love to know about it if there is (don't ever want to have to drop the glovebox again). ;-)

 

[snipboy]

I saw a video on Youtube describing it. Quite an involved process. Couple of levers to pull out of the inside of the glove box, then about 4-6 screws that need to come out.

 

[forbin404]

Maybe I must've forgotten how hard it is to do, compared to my ford van, everything on the acura is a dream to fix.