The trust has four MRI scanners and it received a mobile MRI scanner on Thursday to ensure some appointments could still be carried out.
The machines generate a significant amount of heat when in use, so rely on cooling systems to keep them within safe operating temperatures.
Other hospitals also experienced problems during the heatwave.
The Norwich Spire Hospital took an MRI scanner offline because of a similar cooling issue, while Ipswich Hospital said one of its mobile units was temporarily out of action on Wednesday evening.
Provisional Met Office data showed the hottest June temperature ever recorded in the UK was at Lingwood, a village about eight miles east of Norwich, where temperatures reached 37.7C on Friday.
Do you have a story suggestion for Norfolk? Contact us below.
