For the last couple of days I've had the smell of AC oil in my cabin on start up but still pumping out cold air, I was waiting for it to go pop and it went to day. I just had to go when its pushing 30 degrees and sunny. Now all I'm getting is hot air and no oil smell. I replaced the compressor and dryer unit bout a year ago. The Compressor was 2nd hand so it could be that but I'm trying to work out what could have gone pop to cause the Oil smell to leak in to the cabin and then pump out hot air. I stripped the heater unit out at Easter to replace the heater matrix. I'm about to pop out to check pipes and connections. Any one got any ideas?