marinesniper0318

Hello,

So I replaced the Heater Control Valve tonight and now the air is no longer hot but more room temp (for Miami room temp is still not comfortable ; )...
(I also created a fluid leak as the hose that connect the HCV to the motor is bad, owe well have to drive it until tomorrow afternoon when I get another host and replace it...

So what should my next step to trouble-shoot be...? I am to the point where I just want to hand it off to the mechanic to fix it...should I attempt to fill the freon (r134 or something like that) myself before giving up and paying a mechanic...?

thanks...

Sniper

MainePorsche

Sniper,
Two things:
1- Is you HCV connected in the proper orientation ? Black part should be toward the firewall, not the engine.
2- Do you have good vacuum to your HVAC system ? From the splitter at the Master Cylinder, to the HVAC solenoid under the center console, to the HCV itself.

When engine running and temperature slider all the way to cold (NOT IN DEFROST MODE) where is the lever on the HCV ? All the way up ? All the way down ? Or somewhere in between ?

marinesniper0318

MainePorsche, so yes it is connected correctly with the Black part towards the firewall...and the Vacuum is woking, when I engadget he A/C I see the HVC arm move down closing off the hot water. This is one reason why I have a water leak because the back pressure along with an old 3/4 hose is causing leaking ; )

MainePorsche

So HCV functioning.
Now it's either compressor charge or evaporator soiled/obstructed.
I am assuming your compressor clutch is engaging when you push the button.

ThetaTau87

Is the AC compressor clutch engaging? Have someone push the AC button on/off while you watch the pulley on the compressor. If it is engaging the center of the pulley will spin when the AC is on and will stop with it off.

If the compressor clutch is engaging that means there is at least enough refrigerant in the system to allow it to turn the compressor on. The system is likely just needs a recharge. You should check for leaks to find out why the system is low.

Schocki

What about the pressure lines at the Expansion valve? Is the bigger line cold when the AC is switched on?

PHIL928

There are 3 major issues which can cause a loss of 80% of cooling. The other 20% comes from smaller but more difficult to solve things.
1.) The heater control valve - fixed
2.) The recirculation Flap. Have a look under the dash in the passenger footwell to see if it is sucking air from there. If not you have lost maybe 40% of your cooling.
3.) Check the gas levels. if it's really low you should be able to see a bubble through the glass on the top of the receiver/drier. If it's an 88, then you're porbably still on R12, unless it has been converted.

marinesniper0318

Guys thanks for the input, so I had a friend help me check that the compressor clutch is engaging and he said it was not.

I then took it to a local A/C place and had the refrigerant tested and I was told its good 90% full. They also told me that the compressor is not engaging.

So this may be the ultimate problem, how can I hack or Mickey Mouse it to get the compressor clutch to engage until I can get the whole system replaced or fixed. I am in Miami and it is hot and humid this week...any tricks to engage and keep it engaged are appreciated... also other alternative ideas are more than welcome... ( I cant fix the whole thing now because my 928 specialist told me he could not look at it for 2 weeks )...

thanks...

Sniper

marinesniper0318

Phil928, thanks...to answer your comments...
1) = done
2) = done I made sure the valve is closed and will not open...
3) = gas level 90% or 90lbs anyway they tested it as good...

but no cold air at all...so compressor maybe...I dont care at this point what it is I just want to identify and get it working... ; )

Sniper

PHIL928

Check that the clutch wire is connected. It runs from the compressor up to the front engine wiring harness. It has a connection point in the middle for a tb/wp job, it may have been disconnected

MainePorsche

If fully charged, 2 things regarding clutch engagement.
1- HVAC controller relay failed. Not a quick fix. Search for Dwayne's write up.
2- Freeze switch, and the following can be a quick temporary fix. Find the switch just under the black windshield wiper cowl. It will be a small unit with two wires attached and a thin capillary tube which disappears into the firewall. This switch is part of the clutch circuit and will turn off the compressor when freezing is detected in the evaporator. Join these two wires for a temporary bypass until you get a new switch.

Add: Yes, as Phil said make sure the wire to the clutch is intact and connected

Schocki

Use Dwayne writeup in how to troubleshoot the compressor.

First connect the solenoid of the clutch directly to 12V+ and see if it engages.

Other weak point in the system is the AC relay (search function on how to fix)

MainePorsche

To quickly check whether it's the freeze switch or the HVAC relay, check voltage at freeze switch wires. If you have battery/alternator voltage there, then the relay is good and it is probably the switch itself (could be a low pressure switch down the line, but freeze switch a more common failure). If relay is good and you bypass the freeze switch and still have no clutch engagement then it is the low pressure switch.

marinesniper0318

Phil928, i will check tonight, I pray this is the issue...that would be awesome... ; )

marinesniper0318

Thanks guys, I looked over Dwayne's write up and I just do not have the time nor patience to get that involved... I will however try jumping freeze switch wires and checking that the connected has not disconnected from the compressor...

If that does not do it I will take it to the mech and take my per hour labor beating ... ; )

Sniper