Heater works few minutes then stops. Display

Hi

94 Olds 88. Great car. Good as can be even with 201K but now the cold weather has arrived the following problem has appeared.

I set the temperature on the panel to where the heater kicks in.....it blows hot for a few minutes then I hear a relay type click sound under the dash on the passenger side, the heater blows cold even with the temp set to 90 deg...and the temperature LED display starts flashing.
( but the a/c does not kick in) I then switch engine off....wait a few minutes.. start up again....display normal...heater works for a few minutes then the problem reoccurs.

Anybody out there any ideas....the engine temp is in the mid green and the pipes into the heater are hot.

Thanks in advance. I live a long way from the Olds shop and its getting cold here.

Phil

i have an 82 88royale and the heat went on when the a/c people checked it out they found that the heater core in the firewall had gone bad and needed to be replaced. This might be your problem as well. good luck