Johnson suffered from dehydration Saturday night at Richmond International Raceway and needed five liters of intravenous fluid after the race. He is feeling much better, according to the team, and is set to race this weekend in the Chase for the Sprint Cup opener this weekend at Chicagoland Speedway.
The HMS crew had looked through the car and all of the car components initially appeared to be working correctly on the hot and humid night. But on Wednesday afternoon, the team found that the cooling system had faltered.
"Basically it was blowing warm air," Johnson said in a news release to preview this weekend's race. "It's nice to have a good idea as to what went wrong and why I got so hot in the race car. It's a newer system that we've implemented, so we're just going back to our old faithful system that's worked for years and years.
"We should have the problem rectified."
The six-time Cup champion, who had finished eighth in the race, talked to his crew while sitting in his car after the event. When he got out of his car, he began cramping and laid down on the pit road. He got back up, felt dizzy, laid down again and then was carried by his crew to an awaiting medical cart.
Johnson attended his foundation's sprint triathlon Sunday morning in North Carolina but did not participate.
"There's something that went wrong (Saturday) — it could have been my own nutrition plan," Johnson said Saturday night after spending about 90 minutes in the RIR medical center. "I felt I came in hydrated. We have to make sure all the fans were working in the car. I was warm at the midway point and didn't feel like my helmet fan was working.
"That definitely could cause an issue. I haven't been sick and I had a light week in training as well because I had planned on competing in my triathlon (Sunday) morning. I was well rested. My nutrition and all that was there. It was really bizarre that I got hit as hard as I did tonight with dehydration."