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| Black thing
attached to the underside of the hood that looks like a bunch of tennis
balls |
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The black thing is a vacuum reservoir for the A/C system since the system works via vacuum
pressure rather than via cables. The reservoir increases the volume of
the system's vacuum to enable smooth operation of the vent flaps. A/C'd
cars have 3 vent flaps to operate, in combination with each other depending
on the setting, compared to non-A/C'd cars' 1 vent flap.
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| Center
vent air |
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The stock, factory-installed HVAC system from
1982 to 1993 is built to allow both cooled and heated air to exit the
center vent. See the factory diagram below.
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| Only cold/cool air comes through the side vents |
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Heated air is simply not routed through that part of the system:
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1
Windshield defrost vents: fresh,
cooled or heated air |
2
Side window defrost vents: fresh,
cooled or heated air |
3
Side dash vents: fresh or cooled air |
4
Footwell outlets: fresh, cooled or
heated air |
5
Center dash vents: fresh, cooled or
heated air |
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All vents are temperature controlled,
except for the side dash vents (#3). See
the How-To page for a guide on how to alter the vents to enable heated air
to exit them. |
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| No air comes
out of the center vent and/or floor vent |
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The HVAC system is composed of these main
components: vacuum hoses/tubes, vacuum reservoir, vacuum distributor, vacuum
servos which operate vent flaps and a vacuum check valve. If any of these
components fail, air flow will be affected. It is highly recommended that
you purchase a vacuum pump, such as a MityVac, to test the system and its components. First,
remove the check valve and apply vacuum to the port on the "motor" side of
the check valve while a finger plugs the opposite port. If it fails to hold
vacuum it may be faulty. If it holds vacuum, reinstall it and apply vacuum to the center
vent/defrost servo (remove the hose from the distributor); if it doesn't
hold vacuum or open the center vent flap, this is the cause of the problem.
If it opens the flap and holds vacuum, apply vacuum to the vacuum reservoir
port on the vacuum distributor; if it fails to hold vacuum, this is the
cause of the problem. Lastly, check all vacuum lines and connections for
possible leaks; replace as needed. (Removing the radio and the dash bezel
allow access to the vacuum distributor and servos for testing.)
Click here for the HVAC vacuum diagram
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| Only heated air, or no heat exits the center vents |
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Only heated air:
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The A/C system needs a recharge.
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The control valve is faulty, or is
incorrectly adjusted. The
control valve is located in the engine bay, near the brake fluid
reservoir.
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The control valve cable is faulty.
The cable is attached to the temperature selector on the dash; check to
see if it has become detached at one or both ends, or is binding
somewhere.
No air:
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Vacuum leak somewhere in the system.
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Faulty vacuum servo
(inside the dash).
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Faulty air distributor (inside the dash under the radio, right
side).
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| How
the HVAC controls work (A/C-equipped cars) |
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Max Cool |
Normal Cool |
Comfort |
Ventilation |
Heater |
Defroster |
| Air conditioner is
on. Cooled air is recirculated. Use this setting for
fast cool-down, or short and intermittent intervals only. |
Air conditioner is
on. Fresh outside air is cooled and circulated. |
Air conditioner is
on. Fresh outside air is cooled and circulated. |
Air conditioner is
off. Fresh outside air is circulated; it is heated if heat is
selected (excludes side vents). |
Air conditioner is
off. Fresh outside air is circulated; it is heated if heat is
selected (excludes side vents). |
Air conditioner is
on. Fresh outside air is cooled or heated (excludes side vents) and circulated. |
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| Fan blower works
on only one or two settings, or not at all |
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The fan motor is worn out, the fan switch is
faulty, wires are faulty, or the resistor is faulty. Consult the Bentley
Service Manual for repair information. Also see
this thread and/or
this thread on VWvortex for further information. If the blower fan does
not work on speed 4 but works on speeds 1, 2 and 3, and the A/C works on all
settings, the culprit is most likely a faulty A/C relay.
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| Installing
A/C into a non-A/C car |
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Even though A/C was an option, in the United
States non-A/C Cabriolets are more rare than A/C-equipped Cabriolets.
On the flip side, air conditioning was a very expensive option outside the
States and, in most instances, not really necessary.
All of that being said, if anyone in the USA
requires A/C but has found a fabulous Cabriolet to buy without A/C, keep
looking. Swapping A/C into a non-A/C car just simply isn't worth the
expense or the trouble. If you already own a Cabriolet and want to
install A/C, look into all of your options. Anything is possible, as
the saying goes, but installing A/C is a somewhat complicated endeavor.
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