OPTUS customers in the south-west yesterday were without mobile service for the second time in a week.
Those in Warrnambool were unable to make calls between 7pm and 1am this morning after the air conditioning failed at the phone service provider's Camperdown base station.
Last week a lightning strike in Mortlake left locals without Optus reception for almost a full day as repairs were made to the impacted site.
An Optus spokeswoman said the Camperdown station's equipment automatically switched off once the temperature reached a certain heat.
"Once it was repaired and the site cooled down the equipment went back online," she told The Standard.
"It was constantly monitored and we were there as soon as possible."
Customers with Virgin, which uses the Optus network, may have also been affected in the partial outage.