Volvo Repair: Electrical, direction buttons, sec delay

Question
I just purchace a '93 240 non-turbo sedan.  Seems like a great car, but has some bugs.  
-The check engine light stays on, local mechanic at Volvo says its the air-mass meter.  Checked the fairly smooth running engine by unplugging it and it stalled as usual. Any suggestions?
-The AC stays "on" after flipping the switch to the "off" position.  The unit will stay off if the car is started with the switch off. Checked continuity of switch and local wire, seems ok. ?  

Answer
Hello Rick,  On those models the new 'hot film' mass meter is used.If no heavy black smoke is seen on hard acceleration I would be double checking my 'codes' they rarely travel alone.I have seen throttle switches fail.Its the new style,960/850 type,no adjustment feature.As far as the a/c 'ON' the blower motor will run in the '0' posit.,when the a/c switch is 'ON'.The compressor has a 12 sec. delay function,it rare but the 'delay relay' may be only 're-setting' with the key 'OFF' and not the switch. Its behind the center console RH sd.Aside of the flow direction buttons.Thank You and good hunting!  PKD