Recently our Dimplex electric Fireplace would blow heat out for only about a minute or so, and then no heat. Lights and flame action would still work. After consulting the service manual and speaking to a wonderful customer service rep on the phone, they said to give the heater and fan assembly a good vacuum cleaning. Taking the unit out of the entertainment center was only 4 screws and it's not heavy at all. Cleaned the intake louvers and the squirrel cage fan assembly and put some dry lube on the fan bearings.......all good. The replacement heater/fan assembly was about $160 plus shipping, so if you're having the same problem, give this a try.

While you have it out of the wall you might want to consider changing the incandescent light bulbs to dimmable LED bulbs. Ours had three 60 watt bulbs which I changed to 7.5 watt LEDs. No change to the light effect with the "flames". Bulbs were inexpensive.