Hello all, I know this may sound like a strange question. 
 

In our commercial property the external entrance doors are using Rutland ts3204 door closers. The closers themselves are fine and work desirably most of the time. The issue is that during hot summer times they provide no control and the doors slam extremely hard. We’ve been counteracting this by adjusting them accordingly but it’s becoming a bit of a nuisance. They seem really reactive to heat changes. 
 

Is anyone aware of door closers that are less affected by temperature changes, as I’m sure other doors I’ve used in the past don’t encounter this problem. 
 

Any suggestions would be much appreciated. 

The Rutland trouble shooting guide is here https://www.rutlanduk.co.uk/data/607dd7c17c49d.pdf