Air Condition..I know, I know

joeynat

joeynat

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I searched....just need quick advice.

94 Mark VIII

I turned the air conditioner on a few weeks ago and noticed over a 3 day span the air went from cold to just hot air out of the vents.

Mechanic does dye test no leaks whatsoever.Read He said maybe the freon broke down over time. He flushes the system, charges it up nice cold air again.

Today, no more cold air. Pop the hood and watch the compressor cycle on and off.

I read old LVC threads and bought a VLCM on ebay when this all started but never put it in since I thought problem was solved. If the compressor turns it cant be the vlcm...right ?
 
Freon does not break down. Where do these idiot mechanics come from? I hope he did not charge you.

If the compressor is coming online then things appear to be working. The system has pressure switches that will prevent the compressor from running if the pressure is too low.

Its rare, but I have heard of cases of a Gen one having a blend door issue.

The other possibility is a broken vacuum line. I *think* the color is off-white or black, but its on the passenger side firewall. I think there is also a red line that enters here. Anyway, to make sure its okay. Mine went bad and my HVAC failed. I do not recall what it did, but I think it was stuck on defrost only. The line had worn open from rubbing.
 
When the compressor cycles its from one of two things. Pressure is too high or pressure is too low.

Now your mechanic is special. While refrigerant does break down just like anything it would take more than your lifetime before it did.

Back to the car. If your cooling fan is not on max then the AC system will get too hot and pressure will rise. When pressure rises the system shuts down so it dont explode. So check to make sure the cooling fan is running on high when the AC is turned on.
If the fan is working fine AND the car is at normal running temp yet the system cycles then there is a leak. If your mechanic put dye in it yet cant find the leak then its one of a few things. Hes an idiot or the leak is on the back side of the compressor manifold (good chance) or the evap core is leaking which is inside the dash so you cant really see it.

You are welcome to come by and have me inspect it to narrow the problem down. I am just over an hour drive away.
 
LaserSVT said:
When the compressor cycles its from one of two things. Pressure is too high or pressure is too low.
Click to expand...

Right. I should have been more clear. If pressure is WAY to low, then it will not come on at all. So if the system is out, it will not fire up.
 
Vacuum leak
Blend door
Leak behind compressor
And the Evap Core

So its not the VLCM....

Thats a good checklist guys thanks...

The evap core scares me not looking forward to taking the dash apart. In fact I pray its not that.

LASER im in hillsborough, NJ but the offer is awesome.

Problem is I got to bring it to the mechanic ! I have little time to troubleshoot with a teething 10 month old. Lol.
 
I wonder also if it could be the climate control unit in the dash ? I bought a gen 2 module off of ebay a while back. Wonder if that maybe crapped out ???
 
I would bet $1000 its not the blend door or vac line. Both would have nothing to do with the comp cycling.
Rent a gage kit from Autozone and see how much the pressure drops when the comp kicks in till it kicks off.
 
It's leaking. The dye he used must have been invisible or he just really didn't care. It gave you good cool air because it was freshly charged. It leaked while running or setting and when one leaks, it starts with the compressor cycling off and on until it's so low that there isn't enough pressure for it to cycle on.

It's not the EATC unit or the VCRM. Like Laser said, turn on the AC and check to see if the cooling fan is coming on.
 
Eliminate the middle man

if you get a gauge set you will know for sure if it is low. High pressure sould be about 150 psi to 180 psi. low pressure sould be between 30 psi and 35. if you get those advance auto parts freon bottles with the gauge on it you dont know anything because you dont know if the system has been vaccumed to -30 prior to filling. your gauges will eliminate any guessing and cut out the questionable mechanics out there. Oh if you want to recharge it yourself its really easy but you will need a vaccume. i got one from harbor freight tools for like $40. its paid for itself 100x.

if its short cycling at all it more than likely has a leak. check for dye in the condensation drain.
 
When I seen the compressor kick on and off, the Eatc was set to max ac.

The radiator fan WAS running constant during the cycling. I cant say if it was running fast or slow i thought they ran at one speed.

The only thing I didnt do was shut the A/C off and wait for the fan to kick off.


So whats this telling me now ?

I took the short bus...sorry.
 
joeynat said:
When I seen the compressor kick on and off, the Eatc was set to max ac.

The radiator fan WAS running constant during the cycling. I cant say if it was running fast or slow i thought they ran at one speed.

The only thing I didnt do was shut the A/C off and wait for the fan to kick off.


So whats this telling me now ?

I took the short bus...sorry.
Click to expand...

The EATC is fine and so is the IMRC and you're low on 134a. If the car is cool when you turn on the AC, the fan is going to come on regardless but if the AC is turned right back off, the cooling fan will also shut off within a minute or so, if the car is still cool.
 
Im sorry No Limit but I dont understand. If my fan was running during cycling is that confirming my leak ?

Also, I was driving for 45 minutes then popped the hood to look.

I didnt know the IMRC had anything to do with climate control ?
 
joeynat said:
Im sorry No Limit but I dont understand. If my fan was running during cycling is that confirming my leak ?

Also, I was driving for 45 minutes then popped the hood to look.

I didnt know the IMRC had anything to do with climate control ?
Click to expand...


Sorry, I meant to say VCRM, not IMRC. The VCRM controls the fan and no, the fan coming on doesn't confirm the leak. The fan comes on when the AC is turned on, no matter if the car is hot or cold. I'm on the short bus sometimes too so don't feel bad but seriously, I would say you have a leak and it just hasn't been found yet.
 
get some gauges dude then there will be no more questions. fans kick on. great but you need to know if its low first.
 
once you hook the gauges up post update. then leave the gauges on and see if the pressures go down after 10 15 min. if so.... yo know then comes the fun part.
 
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