Check For Defective Valve; Repairing System For Replacement Of Component Parts; F O Re Ig N M Aterial In Th E System; R E Frig E Ra N T L In E C O N N Ectio N - Chevrolet CHEVY VAN G10 SERIES Service Manual

A IR C O N D ITIO N IN G 1A-22

Check for Defective Valve

The following procedure m ust be follow ed to determ ine if a
m alfunction is due to a defective expansion valve.
1. Check to determ ine if the system will m eet the per­
form ance test as outlined previously. If the expansion
valve is defective, the low pressure readings (evaporator
pressure) will be above specification.
2. The loss o f system perform ance is n o t as evident w hen
the com pressor head pressure is below 200 PSI. T here­
fore, it m ay be necessary to increase the system head
pressure by partially blocking the condenser. D isconnect
the blow er lead wire an d repeat the "Perform ance
C heck" to determ ine if the evaporator pressure can be
obtained.
3. The system will also indicate a low refrigerant charge by
bubbles occurring in the sight glass.
PREPARING SYSTEM FOR
REPLACEMENT OF COMPONENT PARTS
Air conditioning, like m any o th e r things, is fairly simple to
service once it is understood. However, there are certain
procedures, practices and precautions th a t should be follow ed.
F or this reason it is strongly recom m ended that th e preceding
inform ation in this section be studied thoroughly before
attem p tin g to service the system .
G reat em phasis m ust be placed upon keeping the system
clean. Use plugs or caps to close system com ponents and hoses
w hen th ey are opened to the atm osphere. Keep your w ork
area clean.
In removing and replacing any p art w hich requires unsealing
th e refrigerant circuit the following operations, w hich are
described in this section, m ust be perform ed in th e sequence
show n.
1. Purge the system by releasing the refrigerant to the
atm osphere.
2. Rem ove and replace the defective part.
3. Evacuate, charge and check th e system.
W A R N IN G : Always wear protective goggles when
working on refrigeration systems. Goggles J-5453
are included in the set o f air conditioning special
tools. Also, beware o f the danger of carbon m on­
oxide fumes by avoiding running the engine in
closed or im properly ventilated garages.
FO REIGN M A T E R IA L IN THE SYSTEM
Whenever foreign m aterial is found in th e system , it m ust
be rem oved before restoring the system to operation.
COMPONENT PART REPLACEMENT
CAPILLARY BULB
Fig. 2 8 —Expansion Valve
In the case o f com pressor mechanical failure, perform the
following o p eratio n s:
1. Remove the com pressor.
2. Rem ove the receiver-dehydrator and discard the unit.
3. Flush the condenser to remove foreign m aterial w hich
has been p um ped in to it.
4. D isconnect the line from th e receiver-dehydrator at the
inlet screen for the presence o f m etal chips or other
foreign m aterial. If th e screen is plugged, replace it.
Reconnect the line to the expansion valve.
5. Install a new receiver-dehydrator.
6. Install the replacem ent com pressor.
7. A dd the necessary q u an tity o f oil to the system (one
fluid ounce because o f receiver-dehydrator replacem ent
plus th e q u an tity needed for the replacem ent co m ­
pressor — see "Checking Com pressor Oil Charge" under
" Checking O il."
8. Evacuate, charge and check the system.
R E FR IG E R A N T LINE CONNECTIONS
"O " Rings
Always replace the "0 " ring w hen a connection has been
broken. When replacing the "O " ring, first dip it in clean
refrigeration oil. Always use a backing w rench on " O" ring
fittings to prevent the pipe from tw isting and dam aging the
" 0 " ring. Do n o t overtighten. C orrect torque specifications are
as follows:
OUTLET
C H E V Y V A N SHOP M A N U A L