Clubbing 2 ggplots in a single windows and putting 2nd one in Secondary axis-CodePudding

Let say I have 2 ggplots

library(ggplot2)
library(cowplot)
set.seed(1)
data = structure(list(fecha = structure(c(1317452400, 1317538800, 1317625200, 
1317711600, 1317798000, 1317884400, 1317970800, 1318057200, 1318143600, 
1318230000, 1318316400, 1318402800, 1318489200, 1318575600, 1318662000, 
1318748400, 1318834800, 1318921200, 1319007600, 1319094000), class = c("POSIXct", 
"POSIXt"), tzone = ""), TempMax = c(26.58, 27.78, 27.9, 27.44, 
30.9, 30.44, 27.57, 25.71, 25.98, 26.84, 33.58, 30.7, 31.3, 27.18, 
26.58, 26.18, 25.19, 24.19, 27.65, 23.92), TempMedia = c(22.88, 
22.87, 22.41, 21.63, 22.43, 22.29, 21.89, 20.52, 19.71, 20.73, 
23.51, 23.13, 22.95, 21.95, 21.91, 20.72, 20.45, 19.42, 19.97, 
19.61), TempMin = c(19.34, 19.14, 18.34, 17.49, 16.75, 16.75, 
16.88, 16.82, 14.82, 16.01, 16.88, 17.55, 16.75, 17.22, 19.01, 
16.95, 17.55, 15.21, 14.22, 16.42)), .Names = c("fecha", "TempMax", 
"TempMedia", "TempMin"), row.names = c(NA, 20L), class = "data.frame")
data['val'] = rnorm(dim(data)[1], 10000, 1)
data

mycolor = c('red', 'green'); names(mycolor) = c('TempMax', 'TempMedia')
p1 <- ggplot(data, aes(x = fecha))  
        geom_line(aes(y = TempMax, colour = 'TempMax'), size = 1.2)  
        geom_line(aes(y = TempMedia, colour = 'TempMedia'), size = 1.2)  
        scale_colour_manual('color', breaks = names(mycolor), values = mycolor)

p2 = ggplot(data, aes(x = fecha))  
        geom_bar(aes(y = val), stat = "identity", color = 'grey')

The individual plots for p1 and p2 are perfect, however I want to club them in a single plot window with p2 as secondary axis. I took some reference from