Heater only gets hot when engine is accelerated

Good morning,

Sounds like you have air in the system.

There are 2 bleed screws on the system to get the air out. One is on the thermostat housing and the other is at the passenger side front of the motor by the heater hose.

They are 7 mm bleeders.

Open the radiator cap and open the bleeders until only fluid comes out. Then close it. Top off the coolant at the radiator. Then start the motor and run it at 1200 RPM with the radiator cap off until you get heat. Keep an eye on the coolant level and add as needed. That will bleed the system.

Roy