I posted this on the Body and Interior board but no one replied. Maybe I'll have better luck here and someone will help me out .

The underdash vents in my car blow air in all the time regardless of the position of the control lever. To make that even worse its always hot air, unless it's reasonably cool outside. I think the missing hood seal allows the vents to suck in air from the engine bay. I think the vents won't shut off because there's a broken vacuum line in there. I've seen it but I couldn't find the other half of it. It would be great if somebody can post or email me a schematic of the ventilation vacuum lines.
I also have a question about the A/C. Gas leaked out of it and now there is only air in there. Will one of those R-134a conversion kits from Walmart fix the A/C or will I need to take it to an A/C specialist?



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'88 IROC 305 TPI
Crappy 700R4 slushbox
Gutted airboxes
180 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel (gotta luv it)
Ram-air setup coming soon
Flowmaster muffler (puke)
Taylor SpiroPro wires
Accel cap and rotor
Ported plenum
Kills: '94 Z28, Olds Aurora V8, bunch of Mustangs, T-birds, ricers, and others who assumed a 12 year-old car would be too slow.

 

88,

O.K., taken in order...

#1. You'll frequently get a more technical response by posting technical questions on the TECH board. It's simply that there generally are more visitors on this page;

#2. If the air is always discharged from the floor vents, either the damper doors are stuck in position or the vacuum control switch is not working. If the switch has a vacuum source from the engine (fitting on the right rear of the plenum) then the control is likely worn or dried out. There is a film of clear silicone grease in the switch to seal the ports, and it dries out after ten years or so. The switch can be removed, cleaned, and regreased to repair it. Repair the vacuum lines while you're in there;

#3. A missing cowl seal at the rear edge of the hood will really put your system to the task. You need to replace it not only for that but to keep water and debris out of the engine compartment;

#4. R134-a is a conversion substitute for R12, not a replacement. To properly convert, you should repair and evacuate the system, add the correct PAO oil, then refrigerant. The R134-a doesn't work very well in older automotive systems because the compressors and expansion controls are not designed for the higher pressures, and the evaporator is not sized large enough to cool effectively. Your system will be overworked to produce less cooling;

#5. Unless you have the equipment to perform the above procedure, you just answered you last question yourself. If just a little cool air is good enough, then try the 134a if you want. If you want a really cold system, you should use MP39/R401-A instead

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

If you're getting hot air all the time it sounds like your bottom slider on the a/c heater controller is not working. This is a mechanical slide unit. The top slider controls are connected to two round vacuum tube assemblies. The supply vacuum hose comes in (mine is pink) to the left side of the controler to a 2 port round controller. From there it's routed to a 5 port controller on the right side of the unit. Chiltons and Helms have good
descriptions/pictures. These round vacuum controllers have to be tight or they will leak vacuum and not pass vacuum properly to the actuators by the doors. Good luck. I just converted to R134 and had a faulty 5 port controller in back.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Hey thanks for the replies guys!

Actually, let me correct myself. I earlier posted that the underdash vents blow in air regardless of the position of the control lever. I meant to say that the underdash vents work ALSO when the lever is in the OFF position. All the other settings work just fine, i.e. the underdash vents switch off when any other position is selected.

As for the drawing of the system, I don't have access to a Chilton's or Helm's so I would really appreciate if somebody could post a schematic. Vader? I know you have a lot of really cool schematics for just about anything regarding thirdgens .

About the A/C, I'm not looking for supercold freezer blast. I just want enough cool air to keep me comfortable with the windows rolled up in the summer sun. I'm already getting roasted alive by the sun shining in through the T-tops. That hot air blowing in through the heater vents isn't helping much either . I guess one of those kits would give me enough cold air then. I think I'll get the system pressure tested, and evacuated too while I'm at it. No point in wasting $$ if it's gonna leak out in a couple of days anyway.

------------------
'88 IROC 305 TPI
Crappy 700R4 slushbox
Gutted airboxes
180 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel (gotta luv it)
Ram-air setup coming soon
Flowmaster muffler (puke)
Taylor SpiroPro wires
Accel cap and rotor
Ported plenum
Kills: '94 Z28, Olds Aurora V8, bunch of Mustangs, T-birds, ricers, and others who assumed a 12 year-old car would be too slow.

[This message has been edited by 88irocz28 (edited June 17, 2001).]

 

Yeah I get hot air blowing on my legs constantly while im driving! The heater could be OFF and set to COLD adn i still get hot air. I figured it was just from the engine bay

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1992 Pontiac Firebird (stock)
- 305ci V8 TBI / Automatic Trans / Every option, excluding leather
- Killer car audio system:

• Aiwa CDC-MP3 head unit
• Rockford Fosgate 360a2 amp
• pair of 12" MTX Thunder 5000s in a custom box
• Pioneer 3-way 6x9s, soon to add more more more!

 

OK, I finally got a hood seal and now I no longer get that thermonuclear breeze from the engine bay. I also retrofitted and charged the A/C with R-134a. Everything's working great except for a few minor problems.

# 1. The compressor is awefully noisy. It doesn't sound unhealthy, just a steady mechanical clicking sound that I don't like very much. It's also causing this weird buzzing vibration under acceleration or high engine speeds that is quite noticeable.

# 2. Without the A/C engine temperature remains around 160* in city traffic, sometimes dropping to 150* on the highway. With the A/C on, it climbs to 170* on the open road, and about 220* in city traffic, the ambient air temperature being around 79*. I have a 180* t-stat. The primary fan runs all the time and I think the previous owner installed a cooler secondary fan switch because this one runs nearly all the time too, unless it's extremely cold outside.

I find 220* uncomfortably high because I know it will definitely overheat in city traffic in hot weather. As it is my car has a problem with overheating at the most inopportune moments.

The air dam is in place and the radiator and condensor are clean and free of any debris buildup. The water pump is new too.

How can I ensure it doesn't overheat and leave me stranded on the side of the road?

------------------
'88 IROC 305 TPI
Crappy 700R4 slushbox
Gutted airboxes
180 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel (gotta luv it)
Ram-air setup coming soon
Flowmaster muffler (puke)
Taylor SpiroPro wires
Accel cap and rotor
Ported plenum
Kills: '94 Z28, Olds Aurora V8, bunch of Mustangs, T-birds, ricers, and others who assumed a 12 year-old car would be too slow.

[This message has been edited by 88irocz28 (edited June 24, 2001).]