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1966 Corvette: Service Bulletin: Heater Hose Routing Change Required

Subject:   Heater Hose Routing Change Required
Model and Year:   1966 Corvettes with 327 CU. IN. Engine and Air Conditioning
Source:  Chevrolet Technical Service Bulletin
Bulletin No:   DR #66-10
Section:   Ib
Date:    December 16, 1965


On early 1966 Corvettes, with 327 Cu. In. engine and with Air Conditioning, the heater hoses were routed over the Air Conditioning compressor.  Consequently, the high points of the heater hoses are above the coolant supply tank and pressure filling of the cooling system is required to insure a complete fill.  Also, a leak in the coolant system could result in a coolant loss that would not necessarily result in a low or empty coolant supply tank.

Starting with Serial No. 6S103533, Corvettes are being built with heater hose routing similar to 1965 production.  1966 Corvettes with 327 Cu. In. engine and Air Conditioning built prior to 6S103533 should have the heater hoses re-routed as outlined on the following pages.


  1. Drain radiator, then disconnect heater hoses at engine and A/C compressor retainer clip.
  2. Remove existing front and rear A/C compressor brackets.  Discard brackets and four washers indicated in Figure I.  Retain all other attaching parts.
  3. Locate and drill a 19/64" hole in fender skirt as shown in Figure II, View "B".
  4. Install rear bracket (Part No. 3841699) and front bracket (Part No. 3841698) on A/C compressor, using existing attaching parts as shown in Figure I.
  5. Install clip (Part No. 3853968) on A/C compressor bracket using one 5/16-24 x 1 1/4" bolt, nut and lock washer and one 3/8-16 x 2" bolt and nut as shown in Figure II, View "A".
  6. Disconnect heater hose from upper heater attachment and supply tank.  From longer section of hose, make one piece 22 inches long and one piece 2 inches long.  From bulk hose (Part No. 3856866) make new piece 14 inches long.
  7. Attach hoses to supply tank, tee connector, upper heater attachment and engine.  Route 22" hose through compressor clip (Figure II).
  8. Remove and discard hose from water valve to thermostat housing.
  9. From bulk hose (Part No. 3856867), cut new hose 42 inches long and route as shown in Figure II.
  10. Retain hoses to fender skirt with Clip (Part No. 3825416) and a 1/4"-20 x 1/2" bolt and nut as shown in Figure II, View "B".
  11. Install compressor belt and adjust to 100 lbs. using strand tension gauge.
  12. Check clearance between pipe and muffler (attached to rear of A/C compressor) and heater hoses.  If there is contact, very carefully bend muffler to provide clearance.
  13. Refill cooling system until coolant tank remains one-half full.  Start engine and add coolant as necessary to maintain one-half full level in supply tank.

1966 Corvette Heater Hose Routing Change Required

1966 Corvette Heater Hose Routing Change Required

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